Most valuable music catalog?

Tammy and I were having this conversation today when some Michael Jackson stuff was on the news.

Jackson owns the Beatles catalog, which the news said generates 30 million a year - not too shabby!

The Elvis catalog I think generates 15 million a year, if I remember Lisa Maries interview on Howard correctly.

The only other ones that come up as being as strong would be The Rolling Stones, Springsteen and maybe the Who.

Any thoughts on this? I'm very curious as to which catalog generates the most cash.