Note that I referred to Mao Zedong's China and not the China of today, which has embraced a "controlled capitalism" after their flirtation with communism failed miserably (as it always does).
Can you trust the USSR lifespan statistics? I wouldn't.
You cite other countries, none of which are under a purely communist government, because that has never worked out for anyone other than the dictators that ruled them.
I don't think statistics are the issue, or what the exact definition of a communist is. For what it's worth, self-described communists are still in charge in all of the countries I mentioned, with the obvious exception of Soviet Russia.
Let's step back for a moment. I think you should acknowledge that you have constructed a world in your head where communists do battle with capitalists, and capitalists are the good guys.
That idea is outdated and increasingly ridiculous. Clearly it is a narrative that serves the interests of billionaires in West Palm Beach. I don't know that working people buy it. It wasn't communists who put them on a zero hours contract.