I looked this up again in the book: "In particular, according to hukou status, only about 36 percent of China’s overall population is urban and fully 64 percen

I looked this up again in the book: "In particular, according to hukou status, only about 36 percent of China’s overall population is urban and fully 64 percent is rural (some 800 to 900 million people). Owing to uneven birthrates between the cities and the countryside (until recently urban families could have only one child, while rural families often had two or three), China’s children are even more concentrated in rural areas. More than 70 percent of China’s children have rural hukou status today. This means that China’s future workforce is predominantly growing up in rural villages, where educational outcomes are still lagging far behind." Rozelle, Scott; Hell, Natalie. Invisible China: How the Urban-Rural Divide Threatens China’s Rise (pp. 8-9). So the difference here might come from where the population lives vs. their houku status. As I understand it from the book, the houku status dictates where your child is allowed to go to school. So while 36.11% might now "live" in a urban area, many of the children of those urban residents likely will have to live with grandparents in the rural hometown. Unfortunately, this is one of the sections where I cannot quickly find a reference to the source in the book. Maybe if I read the whole chapter again, but I cannot do that right nwo.