How about the fact that the British and the Americans and all the other western governments were shoving opium down their throats? And they were making a pretty penny from all of it. The criminal British empire made their riches from drugging China with opium.
In 1949, when the PRC was formed, they represented 9.5% of the global economy. In 1990, after 41 years of Communist Party rule, China was 1.59% of the global economy.
You cannot blame that on opium or the west, that is the result of Communist policies like the Cultural Revolution and the Great Leap Forward, to say nothing of the ruthless control and censorship of information.
And 1949 is a weird time to try and measure economic output numbers. Half the world in ruins, and China itself being mostly illiterate peasants.. you have a cite for that number? Does it have a dollar figure per capita?