From 'Harlem' (Shake) To (Bruno) Mars, 2013 Hasn't Been Half-Bad
Bruno Mars performs onstage at the 2013 Billboard Music Awards in Las Vegas.

As we begin the second half of 2013, a look back at some of the most notable chart feats from January through June

You've already weighed in on your favorites of the first six months of 2013 in's mid-year awards poll. Let's see how your picks matched up with the songs and artists that made that the biggest chart headlines – 26 below, for the year's first 26 weeks – from January through June.

Jan. 19
"Les Miserables: Highlights From the Motion Picture Soundtrack" jumps 2-1 on the Billboard 200. Meanwhile, a venerable composition from the musical enters the Billboard Hot 100, as Samantha Barks' "On My Own" debuts at No. 97. Although "Les Miserables" has been a hit stage musical worldwide since the '80s, Barks, who plays Eponine in the film adaptation, brings the ballad to the Hot 100 for the first time.

Jan. 26
Billboard debuts the Dance/Electronic Songs chart, the first tally incorporating airplay, sales and streaming for the genre. and Britney Spears score the first No. 1 with "Scream & Shout."

Jan. 26
Banjos on top 40 radio? Yup. Reinforcing pop radio's folk invasion (the Lumineers, Ed Sheeran), Mumford & Sons' "I Will Wait" enters Pop Songs at No. 36, marking the band's first entry on the airplay chart. "Wait" previously topped Triple A and Alternative Songs. "The best-testing songs are the ones we should play most often," Dave Adams, program director of Pop Songs panelist WRNW Milwaukee, advises.

Feb. 2
51-year-old Wanz tops the Hot 100 as the featured artist on Macklemore & Ryan Lewis' "Thrift Shop," which crowns the chart with a 2-1 advance. "At 51 years old, what are the odds that this will ever happen again? Pretty slim," he told Billboard. (Louis Armstrong holds the record as the oldest artist to crown the Hot 100. The late jazz legend was 62 years and nine months old when his "Hello, Dolly!" topped the May 9, 1964, chart.)

Feb. 16
Justin Bieber achieves his fifth No. 1 album on the Billboard 200 as "Believe Acoustic" debuts atop the list. With the arrival, he becomes the only artist to have notched five No. 1 sets before age 19. He was previously tied with Miley Cyrus, who had also posted four leaders before her 19th birthday.

Feb. 23
With a 19th week atop Alternative Songs, Muse's "Madness" rewrites the record for the longest stay at No. 1 in the survey's 24-year history. The track bests the 18-week domination of Foo Fighters' "The Pretender" in 2007. Muse also boasts the next title on the list of those with the most weeks atop Alternative: the trio spent 17 weeks at No. 1 with "Uprising" in 2009-10.

March 2
The Hot 100 undergoes a major shakeup, as YouTube streaming data joins the chart's methodology. Fittingly, "Harlem Shake," the viral smash from Brooklyn producer Baauer, roars onto the ranking at No. 1. "Shake" becomes just the 21st song in the chart's archives to debut at the summit. "When something like 'Harlem Shake' happens, you can't ignore it," Chris Patyk, program director of CBS Radio pop station KEGY San Diego, said. "It feels like a novelty song with a short lifespan, but right now is the time to play it."

March 16
Bruno Mars claims his first No. 1 album on the Billboard 200, as "Unorthodox Jukebox" jumps 2-1 in its 12th week. The set reigns fueled largely by Amazon MP3 sale-pricing, as on Feb. 26, the digital retailer offered a host of albums, including "Jukebox," for just $1.99.

March 16
Bruno Mars wasn't the only beneficiary of Amazon MP3's one-day sale. Billboard was, too! "Joel Whitburn Presents: Billboard #1s: The '70s" roars onto the Billboard 200 at No. 11 following the discounting, marking a Billboard-branded set's highest perch in the chart's 57-year history.

April 6
Justin Timberlake's third solo album, "The 20/20 Experience," debuts at No. 1 on the Billboard 200. Another way to frame his success? Having led twice solo and as a member of 'N Sync, he's just the seventh artist in the Billboard 200's history to notch multiple No. 1 albums both with a group and as a soloist. He joined Beatles Paul McCartney, John Lennon and George Harrison, as well as Eric Clapton, Eminem and Beyonce.

April 13
Darius Rucker rolls "Wagon Wheel" to No. 1 on Hot Country Songs, granting Bob Dylan his latest chart leader, as well. Dylan is credited as a co-writer of the song, as Old Crow Medicine Show's Ketch Secor reworked it from a Dylan bootleg, commonly referred to as "Rock Me Mama." Dylan logs his first Hot Country Songs No. 1 as a writer since 1998, when Garth Brooks' cover of his 1997 composition "To Make You Feel My Love" reigned for a frame.

April 20
Amid a boom of hi-NRG EDM club anthems, stomp-and-clap folk/rock sing-alongs and rap, a simple piano ballad, Bruno Mars' "When I Was Your Man," crowns the Hot 100, reinforcing Mars' star status. The song sports only Mars' vocals and his own piano accompaniment. Only one other No. 1 also features nothing but vocals and piano: Adele's "Someone Like You," which ruled for five weeks in 2011.

April 27
As she crowns the Hot 100 with "Just Give Me a Reason," with fun.'s Nate Ruess, P!nk concurrently collects her first Adult Contemporary No. 1 with prior single "Try." "P!nk has proven that her appeal is not relegated to any one format, genre or demo," noted Adrian Moreira, RCA senior VP of promotion. "I think that her topping AC is a testament to the fact that her songs resonate among a wide swath of fans." Meanwhile, upon learning of her new honor, Pink Tweeted, "Ha!!!!! Mama just got a Billboard Hot 100 #1!!!!!!!!!!!! What!?!?!"

NEXT: May-June

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You've already weighed in on your favorites of the first six months of 2013 in's mid-year awards poll. Let's see how your picks matched up with the songs and artists that made that the biggest chart headlines – 26 below, for the year's first 26 weeks – from January through June.

May 4
Rihanna becomes the first artist in the 20-year history of Billboard's Pop Songs radio airplay chart to tally 10 No. 1s, as "Stay," featuring Mikky Ekko, rises 2-1. She breaks a tie with Katy Perry, who's notched nine No. 1s since her 2008 arrival. Impressively, Rihanna has rung up her No. 1 sum since just 2006, when "SOS," her first leader, reached the summit.

May 18
Macklemore & Ryan Lewis log an historic No. 1 on the Hot 100, as "Can't Hold Us" (featuring Ray Dalton) follows their "Thrift Shop" (featuring Wanz) to the top, making the act the first duo ever to reign with its first two Hot 100 singles. Not even famed twosomes like Simon & Garfunkel, Hall & Oates or OutKast had managed such a career-opening double domination.

May 25
George Strait edges closer to Eddy Arnold's record for the most top 10s in the 69-year history of Billboard's Hot Country Songs chart, as "Give It All We Got Tonight" rises 12-10. The song is Strait's 86th top 10 on the tally, a sum second only to Arnold's 92, which the late legend collected between 1945 and 1980. Strait first reached the top 10 with his introductory chart entry, "Unwound" (No. 6), in 1981. He's sent at least one song into the top tier each year since.

May 25
As they won's mid-year category for "most memorable feud," even Nicki Minaj and Mariah Carey weighed in regarding Billboard charts. The former "American Idol" judges were tied with 44 career Hot 100 hits apiece until May 25, when Minaj debuted two titles and Carey, one ("#Beautiful," featuring Miguel), pushing the rapper into a 46-45 lead that still stands. "All dem #1s. Lol. I guess having a personality, being a secure woman, and giving genuine critique still trumps that," Minaj sneered at Carey via Twitter. Still, "I cannot hold a grudge against Mariah Carey," she added. "What people don't understand is that I've looked up to her for so many years."

June 1
In its 21st week on the Hot 100, and almost nine months after the movie in which she starred opened in theaters, Anna Kendrick's "Cups (Pitch Perfect's When I'm Gone)" reaches the chart's top 40 (44-36). "Anyone that has a preteen will know about this song. 'Pitch Perfect' is a cultural phenomenon and we're very happy to be a part of it," beamed David Nathan, Republic Records senior VP/radio and video promotion.

June 8
Likely aided by EDM's higher profile of late (David Guetta, Calvin Harris), Daft Punk scores its first No. 1 on the Billboard 200, as "Random Access Memories" launches atop the tally (even if the set is more '70s soul than '00s dance). A week earlier, the duo landed its first Hot 100 top 10 with "Get Lucky," featuring Pharrell Williams. Daft Punk had peaked at No. 61 with both of its prior charted songs.

June 8
In surely one of the most bittersweet debuts in Hot 100 history, "Clouds" by late singer/songwriter Zach Sobiech bows at No. 26, fueled largely by strong sales. Sobiech succumbed to a rare and terminal form of cancer on May 20 at age 18. Prior to his passing, several stars joined a tribute clip set to "Clouds," including Sara Bareilles, Colbie Caillat, Jason Mraz, Phillip Phillips and Ashley Tisdale.

June 15
Seven years after she arrived with the song "Tim McGraw," Taylor Swift and the real thing top Country Airplay with their duet "Highway Don't Care," McGraw's 26th No. 1 and Swift's seventh. The song, along with her No. 2 Hot 100 smash "I Knew You Were Trouble." and her perennial pop-culture ubiquity, surely helped Swift win the "first-half MVP" accolade in our mid-year poll.

June 22
Robin Thicke scores his first Hot 100 No. 1, as "Blurred Lines," featuring T.I. and Pharrell, vaults 6-1. "Lines" leaps to the Hot 100's top spot as the chart's top Digital, Airplay and Streaming Gainer. The song is the first to claim all three honors simultaneously since the lattermost award was introduced in March 2012. As we head to the second half of the year, will "Lines" be remembered as the top summer song of 2013?

June 22
Alicia Keys becomes the first artist in the Adult R&B chart's nearly 20-year history to total 10 No. 1s, as "Fire We Make," with Maxwell, rises 2-1. It's her first leader since "Un-Thinkable (I'm Ready)" ruled for 10 weeks beginning three years ago. The new topper is Maxwell's sixth. It's unsurprising that the acts would reign on a duet: Keys has spent the most time at No. 1 on Adult R&B (80 weeks), while Maxwell ranks second (57).

June 29
Imagine Dragons' "Radioactive" climbs 6-4 on the Hot 100, reaching the top five for the first time in its record-setting 42nd week. The song bests the 34-week ascent to the region of Florida Georgia Line's "Cruise," featuring Nelly, a longevity mark set just three weeks ago. As with Mumford & Sons' "I Will Wait" (see previous page), pop programmers are playing hits regardless of where they started: "Radioactive" has logged a crossover from rock to pop and adult radio formats and "Cruise" has navigated from country to pop/adult airwaves.

June 29
Almost 43 years after Black Sabbath debuted on the Billboard 200, the iconic rock band earns its first No. 1 album with "13." It's the band's 23rd chart entry and first studio album with singer Ozzy Osbourne since 1978's "Never Say Die!" The new release is only the group's second top 10, following 1971's "Master of Reality," which reached No. 8.

June 29
One to watch for the second half of 2013: 16-year-old New Zealander Lorde soars onto Alternative Songs with "Royals" at No. 30. The debut is the highest for a solo female making her first visit to the airplay chart as a lead artist since M.I.A.'s "Paper Planes" (No. 28) nearly five years ago. "Not since we launched Gotye ('Somebody That I Used to Know') have we seen such instant reaction," says Dennis Blair, Republic VP of rock promotion.