Atheism and Mass Murder or Killing in the Name of Atheism

As I have meandered around the web, I have seen this topic broached many times - sometimes in the form of - "No one has ever killed anyone in the name of Atheism" or "All mass killings have been initiated for religious reasons" or "Religion has been responsible for all significant historical mass murders" - I'd like to express my skepticism of these and similar statements by posting some research statistics I found a couple of years ago.

Take a look - besides the obvious fact that humans are REALLY good at killing each other - Anybody else see the elephant in the room?