We've been to this club 4 times last year. The numbers of couples and people participating varied widely depending on the night.
Its hard to tell, of course, given that there are several large group spaces and 10 or so private bedrooms, which may or may not have their curtains/doors open for viewing, but I'd say a third or half of total there are sexually active.
Course, as I write this I realize since we don't know the majority of people there, its pretty darn hard to tell who's with the partner they came with and who's with someone different.
Its not like a lightbulb goes off over their heads when swapping occurs!
Its a bit easier, though, when its more than three in the pussy pile.
facelick
dian