With China’s population being more than 4 times that of the US, I would find you guilty as charged, on the basis of not considering the possibility :)
These stats would seem to indicate that either CNY moves much more slowly than USD (which would also surprise me) or that there are also colossal reserves of CNY outside of China (which I believe the Chinese government is actively working to prevent with capital controls?).
Population isn’t that big a factor. India has 36x as many people as Canada, but INR and CAD have about the same total cap.
An explanation could be that people in Chinese save more and keep more of their savings in banks, compared to Americans?
[1] "Currency in circulation" in https://www.federalreserve.gov/releases/h41/20210506/ [2] https://www.bullionstar.com/blogs/jp-koning/how-much-u-s-cur...