Spend enough time on the Internet and you would be forgiven to think that physical music sales died a long time ago. In the real world, though, plenty of people still by CDs (and a few buy vinyl as well). 2011 was a watershed year for digital music sales, though, as, according to Nielsen SoundScan's year-end report for 2011, in the U.S., digital sales finally trumped physical sales for the first time last year. Digital accounted for 50.3% of all music purchases in 2011. In total, 1.27 billion tracks and albums were downloaded last year. That's up 8.4% from 2010.

It's worth noting that the majority of these sales was for single songs. Albums only accounted for 103 million sales. That's up from 86.3 million in 2010, but digital albums still only account for every 1 out of 3 sales in 2011.

Adele's "Rolling in the Deep" set a record by becoming the first song to see more than five million downloads in one year with 5.8 million downloads (it was closely followed by LMFAO's "Party Rock Anthem" with 5.5 million downloads). In total, 112 digital songs exceeded the 1 million sales mark last year.

Streaming

What these numbers obviously don't take into account is the rise of streaming music services. The rise of services like Spotify, MOG, Rdio and even the good old Rhapsody service may just eat into the rise of digital sales in 2012.

SoundScan does track streams, though. Lady Gaga, Rhianna and Nicki Minaj lead the pack here with between 125 to 135 million total streams. The most streamed song of 2011 was Nicki Minaj's "Super Bass" (84 million streams).