I'm not sure you can use tax as a reliable figure. As a corporation, I can write off just about everything, and take a small loss each year -- hence no taxes.
I haven't paid any taxes since 2008 I think -- and then I got it back as an incentive to build the economy.
So, I don't think you can use taxes as a basis, since there are so many loopholes available.
Music on the other hand, can get a bit sticky, as there are some hefty fines. If someone "borrowed" their buddies hard drive, made a copy and played them for commercial use -- they would be looking at hundreds of thousands in fines.
That's why I let my accountant handle it all.