According to the 2008 U.S. Religious Landscape Survey, atheists (who use that label) comprise 1.6% of the population… If there are about 316,000,000 Americans, that means there are about 5,056,000 atheists in the country.
The key word in all that is “about.” There are undoubtedly a lot of Americans who don’t believe in God but who don’t use the “atheist” label. There are probably lots of atheists who lie and just say they’re religious because of the stigma. We also have to consider the margin of error for the survey. In other words, what we have are strong estimates at best. And every survey reveals slightly different numbers.
But not in Egypt. They don’t do estimates in Egypt: