Overall Adult Revenues - $ Rising or Falling?

[Bill]

Dos anybody have any thoughts on how to find good information on wether the overall adult revenues, and especially the online adult revenues, are rising or falling?

I'm talking industry wide, for this question, not about individual or company revenue.

One often hears quoted that $10 billion figure, for adult entertainment overall, but everyone knows by now that's pretty much a made up number. And it's years old.

If anybody knows of a place or document that has any kind of hard numbers or informed estimates, please let me know.