US rap was the most illegally-downloaded genre of music in 2007, with three number one hits featuring singer Akon appearing in the list of popular downloads.
The most frequently traded song on file-sharing networks was Party Like A Rockstar by Atlanta-based rap group Shop Boyz, according to the study commissioned by Wired magazine.
Other songs in the top 10 included Senegalese-American rapper Akon's collaboration with Snoop Dogg, I Wanna Luv U, Don't Matter by Akon and Bartender by T-Pain featuring Akon.
All three songs featuring Akon reached #1 on the US Billboard Hot 100 chart during late 2006 and 2007. The Billboard charts are compiled from radio airplay and sales.
Tracks by US rap and hip-hop artists DJ Unk, Soulja Boy, Mims and Sean Kingston were also in the list. The only pop song included was Justin Timberlake's My Love.
Akon, T-Pain, Snoop Dogg and Justin Timberlake also appeared in the list of most-downloaded artists, a combination of illegal album and singles downloads.
British rock group Radiohead, who released their seventh album In Rainbows as a download in October, did not appear on either list despite appearing prominently on BitTorrent websites.
The film Resident Evil: Extinction – based on a popular videogame – was the most popular movie on file-sharing networks, according to the study.
Other movies in the list included Pirates Of The Caribbean: At World's End, I Now Pronounce You Chuck And Larry, Ratatouille and Superbad.
Surprisingly, one of the year's biggest blockbusters Transformers was only seventh-placed. Other box-office hits Spiderman 3 and Shrek The Third did not appear at all.
The most-downloaded TV show was Heroes, followed by Prison Break, the BBC's Top Gear, Smallville and Desperate Housewives.
The study was undertaken by BigChampagne Online Media Measurement and tracked consumption trends across major peer-to-peer file-trading networks including BitTorrent, Gnutella and eDonkey.
Peer-to-peer file-sharing (also known as P2P) is a method of sharing large files without a central source. Instead of files being hosted on a server and downloaded by several users, files are shared between users directly.
BitTorrent is currently the most popular form of P2P file-sharing.