I might have found some basis for agreement before I read R.J. Rummel, creator of the "democide" (murder by government) concept:
"Now, I estimate that over all of colonized Africa and Asia 1900 to independence, the democide was my original 870,000 [murders], plus 50,000,000 more, and this may be too conservative."
http://freedomspeace.blogspot.com/2005/12/reevaluating-colonial-democide.html
More of Rummel's writings on the concept can be found here:
http://www.hawaii.edu/powerkills/20TH.HTM
Finally, to beat a dead horse, this comes from one of his apostles:
"Every democidal government in the 20th century went to great lengths to ensure they had largely disarmed victims and the general population before it embarked on its killing spree. They can see that an armed population is a real threat to their murderous objectives even if utopian anti-gun groups do not, some of which are run by closet fascists/racists. There are many examples of armed victims successfully defending themselves - a large group of armed Armenian civilians retreated to the hills and fought off attacks by Turkish troops until rescued by British forces in the 20th century's first major genocide, while armed rebels (Rwandan Patriotic Front) stopped the 20th century's last major genocide."
http://www.democide.info/myths.html
If there is any crime that should concern all of us, it's the one that killed over a quarter of a billion people in the last century.