Based on Census data less than 1.7 million self-identify as Atheist. Which would be around .33% of the population. Even if you add up all the people who define themselves as having no religion, different than Atheist, including those who didn't answer, you get around 13% not 16%. And of course there is this.
Seems that by that same math of all who express no religion being one group Atheists represent almost 20% of the Federal Prison Population. That would mean that Atheists are over represented by population wheras Christians are underrepresented. Darn facts. Don't you hate how they get in the way of your talking points?