Four intrepid economists--Wei Chen, Xilu Chen and Michael Song of the Chinese University of Hong Kong, along with Chang-Tai Hsieh of the University of Chicago--have taken a fine-toothed comb to Chinese economic data to try to tease out China's true rate of economic growth since 2008. Not surprisingly, they found that China has been over-reporting its growth rate by an average of 1.7 percentage points every year.

Shave off a little growth every year for the last dozen years ago, and the cumulative effect is that China is now overstating its true GDP by nearly 20 percent.

The four economists' "forensic examination" of China's GDP figures relied on hard-to-fake data like tax receipts, nighttime light intensity observed from satellites, electricity generation, railway cargo and merchandise exports to estimate China's true growth rate since the 2008 Global Financial Crisis. Their estimates are both much more volatile and nearly always lower than the figures reported by China's National Bureau of Statistics.

China's 2018 GDP on China's official statistical website shows that ¥93.15 trillion translates to around $13.4 trillion in U.S. dollars. That compares to $20.5 trillion for the United States, valuing China's economy at about 65 percent of the size of America's. Of course, China has more than four times the population of the United States, so in per capita terms China is still way behind at $9,800 compared to nearly $63,000 for the United States.