Joe,
May I suggest the archives. In August of last year, an American professor, Joyz, inquired about the swinging scene. I do not recall any insights of note, but perhaps an e-mail to the said professor would elicit the needed information. I would place the link her, but my computer skills prevent me. It was determined at the time of the earlier query that no less than 50% of the professors on this board are swingers- quite a figure! I suspect others will come forth, as I am not a professor.
Cheers!