As previously announced, the Billboard Hot 100 songs chart undergoes a major renovation this week with the addition of a host of streaming services to its formula, including those that contribute to the newly-launched On-Demand Songs chart.

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On-Demand Songs measures every on-demand play request and plays from unlimited listener-controlled radio channels on subscription services MOG, Muve Music, Rdio, Rhapsody, Slacker and Spotify. The plays tracked for On-Demand Songs include streams and tethered downloads by both paying and free/trial tier users.

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The Hot 100 will also include non-demand radio streams from Rhapsody and Slacker, on-demand audio streams from MySpace and Guvera, and plays on video request service Akoo. Yahoo! radio streams and Yahoo! on-demand video plays, which were previously part of the Hot 100 formula, will continue to contribute to the chart's rankings.

Additionally, the Hot 100's sales/airplay ratio has been adjusted to both accommodate the influx of additional streaming services to the chart's data pool and to slightly lessen the influence of sales, as the volume of digital downloads had increased exponentially since the chart's last formula modification in 2007.

The chart's new methodology continues to place the greatest weight on sales, with radio the next most influential component, followed by streaming. (Under the chart's new recipe, on-demand streams will be weighted twice as much as passive/online radio streaming).

After all the points were tallied, fun.'s "We Are Young," featuring Janelle Monae, spends a second week atop the Hot 100. The song logs a fourth week at No. 1 on the Hot Digital Songs chart with 322,000 downloads sold (up 7%), according to Nielsen SoundScan, and roars 41-19 in its third week on Hot 100 Airplay with 46 million audience impressions (up 56%), according to Nielsen BDS, granting it the Hot 100's top Airplay Gainer ribbon.

The new streaming data pool helps keep "Young" at the Hot 100's summit, as the track wins the chart's first Streaming Gainer award for the largest increase in streaming activity over last week. The song, which crowns the inaugural On-Demand Songs survey, drew 1.1 million on-demand streams in the chart's tracking week, according to BDS, and boasts a 12% increase in overall streams.

Kelly Clarkson's former three-week Hot 100 No. 1 "Stronger (What Doesn't Kill You)" holds at No. 2. The song bullets at No. 2 on Hot 100 Airplay (118 million, up 1%) and remains at No. 3 on Hot Digital Songs (175,000, down 11%). It ranks at No. 9 on On-Demand Songs with 442,000 streams.

Adele's former two-week No. 1 "Set Fire to the Rain" stays at No. 3 on the Hot 100, despite not ranking on the 50-position On-Demand Songs chart. (It places at No. 32 on overall streams).

The Wanted's "Glad You Came" maintains its No. 4 Hot 100 perch, courtesy of a No. 2 rank on Hot Digital Songs (191,000, down 7%) and a 17-13 jump on Hot 100 Airplay (65 million, up 17%). The boy band's debut single claims the No. 7 spot on On-Demand Songs (472,000).

Gotye's "Somebody That I Used to Know," featuring Kimbra, jumped 9-5 0on the Hot 100. The collaboration, which leads Alternative for a fourth week, holds at No. 5 on Hot Digital Songs (153,000, up 3%) and ascends 50-45 on Hot 100 Airplay (30 million, up 15%). "Somebody" benefits from the Hot 100's expansion of streaming data, as it ranks at No. 2 on On-Demand Songs (776,000).

David Guetta's No. 4-peaking "Turn Me On," featuring Nicki Minaj, rebounds 8-6 on the Hot 100, while Drake's "Take Care," featuring Rihanna, re-enters the top 10 (11-7) at a new peak. The title cut from Drake's second studio album ranks at No. 5 on both Hot 100 Airplay (85 million, up 6%) and On-Demand Songs (496,000).

Snoop Dogg and Wiz Khalifa's "Young, Wild & Free," featuring Bruno Mars, slips 7-8 on the Hot 100, matching its rank on the maiden On-Demand Songs tally (454,000). It's No. 9 on Hot 100 Airplay and No. 10 on Hot Digital Songs.

Rounding out the Hot 100's top 10 are two relatively young songs still establishing on-demand streaming activity, as audience awareness of the tracks continues to grow: Nicki Minaj's "Starships" (6-9) and Katy Perry's "Part of Me" (5-10). "Starships" holds at No. 4 on Hot Digital Songs and pushes 38-31 on Hot 100 Airplay, while "Part" remains at No. 7 on Hot Digital Songs and edges 14-11 on Hot 100 Airplay.

"Starships" and "Part" rank at Nos. 13 and 41, respectively, on On-Demand Songs. The tracks, each in their fourth weeks on the Hot 100, gain by 24% and 41%, respectively, in overall streaming.

Check billboard.biz tomorrow (March 15), when all rankings, including the Hot 100, Hot Digital Songs, Hot 100 Airplay and On-Demand Songs, will be refreshed, as they are each Thursday.