First of all, I turn 23 in a Month.
I would say about 90% of the 1349 songs on my iPhone are legal. Quite a few have been purchased through the iTunes store, and the rest are old CDs I have/had. I only illegally download songs when they're not in the iTunes store, as about 99% of illegally downloaded songs don't match the audio quality of iTunes AAC's.
I realize I'm in the minority of people my age, but I feel that I should support artists whom I find add something to the fabric of American musical culture.