According to the 1800 US Census, 17% of the US population back then were slaves. This seems rather hard to square with a graph claiming that more than 80% of the labor force were "free agents".
I think Morgan's figures may have excluded slaves. They weren't paid a paycheck either, so they fall in neither category.
Yes, I was suspecting that the underlying data excluded slaves. Not sure I buy the "paycheck" argument --- presumably in the less tamed regions of the US, there were plenty of other people who hardly ever handled money.