erestingly, during that same time, people have been buying more music than ever. How is that possible? It's because the iTunes Music Store popularized the cheap digital single. After manhandling the major record labels during a series of now-legendary negotiations, then-Apple CEO Steve Jobs was able to initially offer digital albums for $10 and any individual track off that album for 99 cents.

Ds -- by a wide margin -- generating 819 million sales to just 500 million for the CD.

That changed the music industry forever. When music sales reached their peak in 2000, Americans bought 943 million CD albums, and digital sales weren't even a blip on the radar. By 2007, however, those inexpensive digital singles overtook C

ording to the RIA

pple's iTunes is behind that sea change. According to NPD estimates, iTunes is currently responsible for 63% of all digital music sales. Even after the emergence of competition from Amazon and Google.

The popularity and ease of downloading cheap digital singles has transformed the industry. Not since the vinyl era has the single been this popular. The smaller, cheaper "45" record dominated music in the 1950s and '60s, but the music industry wised up in the '70s.

Vinyl, cassette and CD singles were always cheaper for consumers, but manufacturing costs were not. Nor was the space required to house them in stores. Thus, the single became harder and harder to come by.

The reality is if singles were as available a decade ago as they are now, they would have been just as popular. Music nerds notwithstanding, the average music listener has really only cared about a few tracks off an album at most.