How many people having sex on any given moment

Walking the streets today there were quite a number of very attractive looking ladies about and it got me to thinking - somewhat adolescently I admit - to how many people were having sex at that moment. And i was willing to be open-minded about it too, not just PiV but just about kind of intimate play, hetero, homo, oral, anal or whatever.

Back home I looked the question but found very widely varying answers, most backed up by mathematical reasoning and calculating, but all based on various different assumptions. I found 166 666 (give or take a few thousand) to over a million and many others.

So, my query is, does anyone have any opinions or answers? Any references or sources to back up a reasonably believable number?

An important corollary to that question is how many of those are using contraceptives and/or can actually pay for or be responsible for their spawns without the government taking, or asking me for my money.

Answer: much fewer than I would like to see.

And how many are actually enjoying it?

(and how many have my combination of fetishes?)