Filesharing and cyberlocker sites accounted for less than a third of illegal music acquisition in 2011, according to a leaked report of an NPD study from the RIAA obtained by Torrentfreak.  The bulk of music piracy was from offline sharing, including burning/ripping from others’ CDs and hard drive trading.  Around 65% of all music acquisition was from illegal sources, according to the report. 
In terms of legal music acquisition, paid downloads (19% of all music acquisition) now top physical CDs (16% of total music acquisition).
The RIAA report, marked "confidential" according to Torrentfreak, reveals that the industry association’s ongoing crusade for new legislation against filesharing sites hasn’t been directed at the biggest sources of illegal music acquisition.
While the trends in digitization and piracy of video and books are not parallel to those in music for a variety of reasons, the trends in music bear watching since the process of digital change started with music and are further along than in any other medium.