24 years ago I read one book called 'Starlin's Secret War' in which I remember it says Starlin killed the same number of people as the number of the dead at war in Russia. I checked at Wikipaedia about the number of the dead at WWII, which was 23.6 million. Probably the description of the book was something like at WWII Russia lost 20 million people and Starlin killed the same number of people in execution, purge, sending them to gulag, etc.

According to Wikipaedia the number of the dead at WWII in each country was China; 19.6 million, Germany; 7.5 million, Japan;2.6 million.