Average Lifespan
http://www.longevitymeme.org/articles/viewarticle.cfm?page=1&article_id=11
As for when people have sex, there is no real sexually active time in one's life, although I did calculate the first 15 years as not having sex at all. I know MANY people who would laugh that I did so. As for when sexual activity ends - it doesn't. The average number of times a person has sex over his/her lifetime is just that - an average. Averages are used to take into account the nerd who lives across the hall who hasn't had any in the last 5 years as well as the nympho upstairs who can't go 5 hours without it.
http://www.indiana.edu/~kinsey/resources/FAQ.html#frequency
http://www.durex.com/cm/gss2005Content.asp?intQid=778&intMenuOpen=
Just to show a couple of the studies I used to determine the number of times the average person has sex.
If you wanted an accurate figure, you'd also have to take into account population densities and time of day. For example, since China has the most dense population and sex is most likely to occur in the late evening, more people would be doing it at, say, 1200 GMT (10 pm in Beijing) than at 10 pm over the far eastern coast of Greenland, or 2100 GMT.
This also doesn't take into account those in the sex industry, acts of sexual violence, or sexual encounters that do not end in intercourse. So take it any way you want, but right now, truly, millions and millions of people are doing it somewhere, lol.
