World population

I've added a new column for estimated world population figures, and filled it in from 1950 to 2009 using United States Census Bureau data. I'll top it up with estimates for earlier years when I've decided whose data to use.

It turns out that something I knew about world population - that most of the humans who have ever lived are alive today, or to put it another way, that more people haven't died than have - is not true. It's not even close to true. It isn't even close to believable once you've thought about it for any length of time. An estimate of the number of people who have ever lived by the Population Reference Bureau in 2002 plumped for 106 billion, so the percentage of those who are lucky enough to be still with us is about 6%.
That also happens to be the percentage of people alive today who are on Facebook. That means only 0.36% of people who have ever lived are on Facebook, so I think I can hold out for a while longer.

History xls: the history of the world in a spreadsheet