Irreligion by country

http://en.wikipedia.org/wiki/Irreligion_by_country

Irreligion (encompassing agnosticism, atheism, nontheism, ignosticism, antireligion, skepticism, freethought, antitheism, apatheism, non-believer, secular humanism, marxism, or deism) varies in the different countries around the world.

1.1 billion people (16% of the world population) are considered non-religious.