I looked it up, the actual winner on a per capita basis was San Marino (3 medals, one per 11,310 population).
If you only look at “real” countries with significant populations, then it’s New Zealand and Jamaica doing the best.
The USA was 59th on this list.
I’m not entirely sure this would be the best framework but it’s hard to say how to balance the population factor, I mean let’s compare Canada (36th) and the USA, these are probably close to being equal so that the square root of population would come closer to being a good test.
Also if you’ve finished ahead of all countries with larger populations, that establishes a sort of chain of superior Olympic countries. That chain looks like this as all these countries finished higher per capita than any nation with larger populations:
1. San Marino
2. Bermuda
3. Grenada
4. Bahamas
5. New Zealand
5. Netherlands (9th)
6. Australia (14th)
7. Great Britain (26th)
8. France (40th)
9. Russia (41st)
10. USA (59th)
11. China (78th)
So these were the only nations who beat all larger than themselves, China of course has to be in the list. The only way for the USA to avoid the list is to finish below China and India as the fourth highest population goes to Indonesia which finished 91st of 93 (India 93rd, Nigeria 92nd).
How many of those athletes from other countries actually live and train in the US full-time?
You can pretty much pick the country you compete for now, even if you never lived there.
I presume you did your calculations (post #39) based on the total medals. I did both that and the weighted medal count (5 for gold and 3 for silver), and the USA did slightly better with the latter (8 places higher).
However, I used the population figures from Worldometer, and there were a few discrepancies which, to save time, I didn’t adjust for (Kosovo, Korea, Puerto Rico and Turkmenistan), so my figures might be slightly out (which is why I haven’t included them), which probably accounts for the small differences between your figures and mine.