Because that number is about public companies. Many people run their own business, which might be not public, but they own "shares". Most Western countries have

Because that number is about public companies. Many people run their own business, which might be not public, but they own "shares". Most Western countries have a wealth of prosperous SMEs. People who invest in someone else's company very likely do so because have no better option, e.g. to invest in her own company for growth. Btw please define "US stock". US tax resident? Listed on US the stock exchange? Owned solely by US citizens?