A new global survey on religiosity (PDF) by WIN-Gallup International has two big findings:
First, the United States has gone from being 1% godless in 2005 to 5% in 2012. (The percentage of people simply calling themselves non-religious is 30%, significantly higher than ever before.) That jumps us up quite a bit on the Global Atheism Index:
The other finding is that atheists are now 13% of the world population, an increase of 9% since 2005:
… the number of self-declared atheists in the world has risen by 9% since the measure was last taken in 2005.
The massive poll, conducted in 57 countries (not, apparently, including Britain) among 51,000 people asked a single question “Irrespective of whether you attend a place of worship or not, would you say you are a religious person, not a religious person or a convinced atheist?”
It shows that on average 59% of the world said that they think of themselves as religious, whereas 23% think of themselves as not religious and 13% think of themselves as convinced atheists. Naturally there are enormous variations from country to country.