Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.
This blog post contains a breakdown of SO users by country, but it's quite old.
It is possible to make another one with updated data? Thanks.
EDIT: this was just posted on http://blog.stackoverflow.com/2010/12/stack-overflow-2010-analytics/ :)