Digital music sales almost doubled worldwide in 2006, but that still wasn't enough to make up for the loss in CD sales, according to a new report.

The International Federation of the Phonographic Industry's 2007 Digital Music Report (pdf) found that global digital music sales not only doubled in 2006 but also may account for a quarter of all music sales by 2010, CNET reports. Overall music sales were down 4 percent in the first half of 2006, according to IFPI.

The total number of legally downloaded digital tracks topped 795 million last year, up 89 percent from 2005. The number of available digital tracks also doubled, to 4 million, via more than 500 online music services available in 40 countries.

While the music industry says illegal downloads continue to erode legal music sales, many outside the industry maintain that the industry's insistence on encrypting most digital tracks with Digital Rights Management is what's stunting sales.