So, I came across this on the BBC's website today. It was set up in recognition that world population has recently reached 7 billion people. Entering your date of birth gives you an estimate (calculations provided by the UN Population Fund) of how many people lived on the planet the day you were born.
When I was born in 1983, I was the approximately 4,674,308,819th person on the planet. When my father was born in 1950, he was approximately the 2,540,487,787th person on the planet.
For anyone who might be interested, here is the U.N. Population Fund's State of the World's Population 2011 report released on October 26, 2011.
