Well, you can have all these charts to say that people are buying less music, yes.
But that doesn't take into effect that the majority of "music" produced today is over-produced piles of shit, regurgitated by the same few groups of people, with identical canned rhythms and beats. That doesn't take into effect the fact that most CD's today are "over-mastered" and sound like crap. That doesn't take into effect the fact that most musical "talent" today is more about tits and ass, and less about actual, y'know, MUSICAL TALENT.
Brittany Spears, anyone?
You can whip out all the charts you care to, but if you want to understand the reasons behind the music industries decline all you have to do is look at the so-called quality of the music being put out. THAT is why the industry is dying.