Somewhere someone asked something about US swimmers swimming for other countries. The bigger trend in swimming is foreign swimmers coming to the US to train, mainly through NCAA swimming.
Six foreign athletes training in the US won 8 golds, 2 silver, and 4 bronze for 14 total medals (2.33 per swimmer). That is 5% of actual medals awarded. Relays bump actual medals up above what gets counted in a medals table. But the only foreign swimmer training in the US to win a relay medal was Marchand. So in this case, only the denominator is increased.
The denominator is 219 (awarded to 125 swimmers, or 1.752 per swimmer). The US earned 69 total medals (again, actual medals) by 34 swimmers, or 2.03 per swimmer.