Katy Perry performs "The Prismatic World Tour"

Katy Perry performs onstage during "The Prismatic World Tour" at PNC Arena on June 22, 2014 in Raleigh, North Carolina.

Kevin Mazur/WireImage

Six months into the year, Katy Perry's "Dark Horse" leads the pack as 2014's most-streamed track in the U.S., according to Nielsen BDS. Since January, the title has received more than 188 million pays across streaming services such as Spotify, Rdio, YouTube and more.

1.24 billion plays were accumulated by the top 10 most-streamed tracks in the U.S. in the first six months of 2014. Compared to last year's top 10 total at this time, that's a decrease of 7 percent (81 million), but that difference deserves as asterisk, as last year's mark was achieved thanks in part to Baauer's "Harlem Shake," which racked up an astronomical number of January-June 2013 streams (438 million in the U.S.) thanks to user-generated content from the YouTube dance craze that the song's epic bass drop inspired. That 438 million sum is 2.3 times the number of views that the more traditionally-viewed/played "Dark Horse" garnered in the first half of this year.

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"Dark Horse," like all the titles among the top 10 most-streamed of 2014 so far, benefited heavily from its official music video, which has drawn more than 400 million global views to date. The title, which was already a No. 1 across streaming services purely based on data from audio on-demand providers like Spotify and Muve Music, reclaimed the No. 1 spot on Billboard's March 8 Streaming Songs chart upon the release of its Egyptian-themed video. With eight total weeks at No. 1, "Dark Horse" is the longest-leading Streaming Songs chart-topper of 2014.

With nearly 145 million U.S. plays, John Legend's piano ballad "All of Me" boasts the second-most streams on BDS' mid-year streaming chart, right above a track at the opposite end of the sonic (and lyrical) spectrum, Jason Derulo's cheeky "Talk Dirty," featuring 2 Chainz (142 million).

Those songs rank above Pharrell Williams' worldwide phenomenon "Happy," which reached No. 1 on Streaming Songs for four weeks in May and has tallied more than 135 million U.S. streams since January. "Happy," whose online streaming activity was jump-started by its unique 24-hour music video, benefits from a high volume of user-generated plays from fans all over the globe making their own dance videos to the song.

Rounding out the top-five most-streamed songs so far this year, Idina Menzel's "Let It Go" has totaled 129 million streams. "Go" reached No. 2 on Streaming Songs, powered by the popularity of its parent album, Disney's "Frozen" soundtrack, the top-selling album of the first half of 2014.

2014 MOST-STREAMED SONGS, according to Nielsen BDS (YTD)

1. Katy Perry Feat. Juicy J
Dark Horse
Capitol
188,236,000 streams

2. John Legend
All Of Me
Columbia
144,669,000 streams

3. Jason Derulo Feat. 2 Chainz
Talk Dirty
Beluga Heights/Warner Bros.
142,478,000 streams

4. Pharrell Williams
Happy
Back Lot/Columbia
135,197,000 streams

5. Idina Menzel
Let It Go
Walt Disney
129,128,000 streams

6. Iggy Azalea Feat. Charlie XCX
Fancy
Def Jam
111,911,000 streams

7. Pitbull Feat. Ke$ha
Timber
Mr. 305/Polo Grounds/RCA
106,081,000 streams

8. DJ Snake & Lil Jon
Turn Down For What
Columbia
102,340,000 streams

9. Beyonce Feat. Jay Z
Drunk In Love
Parkwood/Columbia
92,694,000 streams

10. OneRepublic
Counting Stars
Mosley/Interscope
91,494,000 streams

11. A Great Big World & Christina Aguilera
Say Something
Epic
86,581,000 streams

12. Miley Cyrus
Wrecking Ball
RCA
83,736,000 streams

13. Ariana Grande Feat. Iggy Azalea
Problem
Republic
82,694,000 streams

14. Passenger
Let Her Go
Black Crow/Nettwerk/Warner Bros.
82,672,000 streams

15. Bastille
Pompeii
Virgin/Capitol
80,755,000 streams

16. Lorde
Royals
Lava/Republic
79,720,000 streams

17. Eminem Feat. Rihanna
The Monster
Web/Shady/Aftermath/Interscope
72,762,000 streams

18. PSY
Gangnam Style
YG/SchoolBoy/Republic
72,706,000 streams

19. Chris Brown Feat. Lil Wayne & French Montana OR Too $hort
Loyal
RCA
70,537,000 streams

20. YG Feat. Jeezy & Rich Homie Quan
My Hitta
CTE/Def Jam
69,137,000 streams