-- Iggy Azalea: Coinciding with the April 22 release of her debut full-length "The New Classic," Azalea's "Fancy," featuring Charli XCX, jumps 4-1 on Hot Rap Songs. The last time a female with lead billing had led the list was in 2011 when Nicki Minaj's "Moment 4 Life," featuring Drake, ruled for nine weeks. Overall, Azalea is the 14th woman to hit No. 1 as a lead act. On Hot R&B/Hip-Hop Songs, "Fancy" jumps 11-6 as the Airplay Gainer, thanks to a 27 percent rise to 29 million impressions. It vaults 37-18 on the Hot 100.
-- Paramore: Almost seven years after it first appeared on the chart, the band achieves its highest Hot 100 rank with "Ain't It Fun" (26-21), powered by a 24-14 blast on Radio Songs (51 million impressions, up 21 percent, according to Nielsen BDS). "The Only Exception" (2010) and "Fun" predecessor single "Still Into You" (2013) each reached No. 24 on the Hot 100. Lead singer Hayley Williams had an idea "Fun" would be a hit: "You're gonna hear this a lot on the radio next year. Get used to it," she warned before performing at Z100's Jingle Ball in December.
-- Imagine Dragons: The band achieves a feat that only three other acts have in the Hot 100's 55-year history: two of its songs have each tallied at least a year on the chart. "Demons" (29-32) logs a 52nd week, joining "Radioactive" (42-48), which extends its longevity record with an 86th frame. (The group is the only act to chart its two such hits simultaneously.) The other artists with two titles that each spent a year on the Hot 100: Faith Hill ("Breathe," "The Way You Love Me"), Lifehouse ("Hanging by a Moment," "You and Me") and Train ("Drops of Jupiter (Tell Me)," "Hey, Soul Sister").
-- A Great Big World & Christina Aguilera: "Say Something" advances 2-1 on Dance Club Songs, marking A Great Big World's first leader (and appearance) on the list and Aguilera's eighth No. 1. Remixes (although not available commercially) by Marc Stout, Riddler and Bent Collective, among others, helped power "Something," a ballad in its original form, to the top. The song dips 30-35 on the Hot 100, where it peaked at No. 4.
-- MKTO: Aided by new airplay on New York's Z100 (WHTZ), which played "Classic" 23 times in the tracking week ending April 20, the song reaches the Hot 100's top 40 (51-39). It leaps into the top 20 (26-19) on Digital Songs (65,000, up 41 percent).
-- Fitz and the Tantrums: "The Walker" (No. 71 on the Hot 100) rises 2-1 on Alternative. It's the band's second No. 1, following last year's first chart entry "Out of My League." How rare is it for an act to take its first two charted Alternative titles to No. 1? Only three acts in the chart's 25-year history previously did so: fun. (2012), Alanis Morissette (1995) and Green Day (1994).
-- Nico & Vinz: Spotlighted as a Bubbling Under act earlier this month, the Norwegian duo makes its Hot 100 entrance with "Am I Wrong" (No. 91). The track leaps 34-23 on Pop Digital Songs (24,000, up 83 percent), 32-26 on Mainstream Top 40 and 34-27 on Adult Top 40.
-- Phillip Phillips: He becomes the fourth graduate of Fox's "American Idol" to tally at least three Adult Top 40 top 10s, as "Raging Fire" burns 11-10. The show's 2012 champ matches David Cook's sum, with the singers trailing only Kelly Clarkson (13) and the Chris Daughtry-led Daughtry (nine). "Idol"s Kris Allen, Adam Lambert and Carrie Underwood boast one Adult Top 40 top 10 apiece.
-- Sergio George Presents Salsa Giants: The grouping hops 3-1 on Tropical Airplay with "Bajo La Tormenta." The tropical collective is comprised of salsa heavyweights, including Tito Nieves, Luis Enrique and the recently departed Cheo Feliciano, among other icons of the genre.
Additional reporting by Wade Jessen, Amaya Mendizabal, Gordon Murray, Rauly Ramirez and Emily White