How large (or small) is the audiophile market?

Just curious, how big is the total market for audiophile hardware?  There seem to be a lot of manufactures vying for a a small pool of potential buyers.  I've read in places that as boomers age the market is shrinking.  I don't know very many young people, but none that i do know are into it.  Anyone have any idea what the total market size is?