I don't know the stats behind that, but it also depends on when communism began. It wasn't with Marx, but long before. Marx just collected all the bad ideas in one place, coupled it with a short-sighted and historically incomplete and misleading story. It took off from there.
Communism and other bad ideas thrive where people know just enough to hurt themselves. There is no human learning by osmosis - see Hilary Clinton.
My suspicion, after having dealt with liberals for so long is that the Ten Commandments is true. Men will make for themselves gods of their own liking. These gods may even be themselves. This is why God made things so clear - wrongful worship is natural. It takes effort to worship the True God. Centralized Planning is the creation of egomaniacs blind to their own limitations.