In a better world, everyone would have sense of history. Economists would learn economic history along with economic theory. But in our second-best world we do have great books like Angus Maddison's The Contours of the World Economy, 1-2030 AD.
The book is full of interesting data and analysis. Maddison's China/world GDP per capita ratio (1990 $) trend goes from 1.06 in 1500 to 0.2 in 1973 to 1.33 in 2030 (Table 3.25).
Coincidentally, I just looked at "The Wonder Years: Boom times in a Chinese village" in the March 31 New Yorker.
Can Maddison's optimisic forecasts be squared with accounts such as this? I have no idea but the question is more than fascinating.