This map shows the results of a survey of 40 countries that measures the percentage of atheists in each.
China and Japan had the largest percentage, which is not a surprise. The numbers in general are not large but what I find interesting is that the media now treats the issue of atheism as noteworthy and worth following.
It turns out that there are significant number in Saudi Arabia, of all places. Not surprisingly, they live secret lives, maintaining a façade of belief while sharing smuggled atheist works.