School project on how the music industry has changed from the internet

#1
Pretty much what the title says.

I was wondering the quarterly sales on itunes compared to the quarterly sales at a store that distributes CDs, like FYE, best buy etc.

Also, I was wondering if anyone knows how much percentage of the sale the music industry gets from a CD sale compared to an Itunes song sale.

Finally, I was wondering the amount of music being pirated illegally on programs like limewire every year.

Thanks. It would help.
#2
Do some research. Sales figures get published, as do studies into use of various technologies. A little googlemancy and wikiing and you've got all you need.