A recent poll conducted by WIN/Gallup International concluded that ~13% of the globe self-identifies as atheist (more than twice the percentage seen in America). Here's how those atheists are distributed around the world.
Via the Washington Post:
The highest reported share of self-described atheists is in China: an astounding 47 percent. Faith has a complicated history in China. The state is deeply skeptical of organized religion, which it has long considered a threat to its authority.
In the Taiping rebellion of the 19th century, a religious cult started a Chinese civil war that killed millions of people and left the country exposed to European powers. The official ideology of the Communist government scorned both “new” Western religions and more traditionally Chinese faiths, destroying countless temples and relics during the Cultural Revolution of 1967 to 1977. While today’s Chinese leaders do not seem to share Mao Zedong’s fervent belief that China’s rich religious history was holding it back from modernity, nor do they seem prepared to bring that history back.