Context: Joseph Stalin is said to have killed roughly 23 million people of the USSRs population of around 194 million people. That is 11.85% f the population.
Meanwhile, Adolf Hitler, while he did kill less in number, only around 17 million people out of Nazi Germanys population of around 109 million at its peak, he killed more in percentage. Around 15.59% of the population.
But then, Pol Pot who led Democratic Kampuchea from 1975-1979 is said to have killed anywhere from 1.5-2 million people out of Kampucheas 7.8 million people. The lower figure is 19.23% f the population and the higher is 25.64% f the population. Pol Pot killed the most people as a % of the population of any dictator in history. The effects were severe: Life expectancy fell from 40 to 12.
(I am using approximated figures that may not be 100% correct, these figures vary a bit) #history