Schooling in China increased from 1.5 years in 1950 to more than 7.5 years in 2010 according to Barro-Lee (http://www.barrolee.com/). The returns to schooling increased from only 4% in 1985 to 16% in 2002 (https://ideas.repec.org/p/wbk/wbrwps/7020.html).
