Sounds interesting - would make it about the size of Microsoft
Some market cap vs annual revenue ratios:
Microsoft (MSFT) $255bn market cap - $72bn revenue - ratio 3.54
Apple (AAPL) $437bn market cap - $128bn revenue - ratio 3.41
IBM (IBM) $224bn market cap - $107bn revenue - ratio 2.09
average market cap / revenue of above: 3.01
this avg ratio would estimate a total annual revenue of about $83bn for all MPAA members.
http://news.ycombinator.com/item?id=3245520