You're beating a dead horse by mentionning the "per capita" argument. It has already been said 10000 times that it is impossible for large countries to compete on this basis because of various factors that I wont explain here , that would be too long.
Kosovo finished high because one single athlete managed to win a medal, the same way Grenada, an island of 100,000 as been performing well above their weight in the last two olympics because of the lone Kirani James.
In order to perform as well as such a small nation, the US would have to win 3000 medals for one won by them (there is a total of only about 970 medals distributed in one summer olympic).
When compared with Croatia, the USA would have to win 82 medal for one medal won by a Croatian athlete (China, about 350). This is impossible. There is a limited number of sport, athletes allowed to compete for medals, athletes allowed to compete. Some sport allow only one athlete per nation to enter, some distribute several bronze medals, etc..
The per Capita argument is generally used by people with inferiority complex ....