If we accept the figures of Marek Sliwinski, Pol Pot killed about two million people, and thus a little more than a quarter of his countrymen.
If we assume that there were five hundred million people living in China in 1949, the death toll from a "social experiment" of the type perpetrated by Pol Pot would have been one hundred and twenty-five million.
This can be compared to the fifty million deaths that, according to Frank Dikötter, resulted from the famine caused by the "Great Leap Forward" of 1958-1962.