Rate of having sex

There are 7 billion people in the world.
Let me guess that the average person has sex once a week for half his/her lifespan.
That means that every week there's 0.5*7 billion = 3.5 billion people having sex.
There are about 10.000 minutes in a week; so on the average 350K people start having sex every minute.
The average sex-act may last for 15 - 30 minutes.

According to The Penguin Atlas of Human Sexual Behavior...
Sex occurs 120 million times a day.
240 million people have sex daily (roughly).
That's...
10 million people an hour.
or
166,666 people a minute.
(Since the Atlas was published in 2000, when world population was just under 6.1 billion, these numbers should be slightly higher today).