I just ran across an interesting web page, part of a larger site with data on religious statistics worldwide.

http://www.adherents.com/

Data on world atheism and nonbelief.

Enjoy!

An interesting thing that is very unappreciated by people, is that atheism is more universal than any given religion in both time and place.

There are atheists in every single country in the world, and have been atheists in every civilization in history (one can assume the latter). No religion can ever make this claim of course.