It's amazing that not much longer than a decade ago, the idea of MP3s or music without a physical CD was virtually non-existent. Since then, it's come to be the medium of choice and the driver of music sales today. The latest Nielsen report for 2012 shows an increase in overall music purchases, driven by digital sales.
Here's eight years of music sales data from the Nielsen Company and Billboard:
While physical CDs still remain the dominant format for albums, digital albums are increasingly the medium of choice. In fact, if you include all individual digital tracks sold at a 10 track to 1 album ratio, digital is the more popular format. And many people are buying their favorite tracks they like off an artist's album and choosing to forego the rest of the album.
Also interesting as a sidenote, is the uptick in LP album sales.