What exactly constitutes a 'major technological advance'? If we're counting Turing Awards by university affiliation, then I believe 90% is probably a good estimate for the US share (https://en.wikipedia.org/wiki/List_of_Turing_Award_laureates...). If we're counting Nobel Prizes in Physics, Chemistry and Medicine, it suddenly becomes less clear why this should be true (https://en.wikipedia.org/wiki/List_of_Nobel_laureates_by_uni...), and if we're counting the number of Fields Medals (the most relevant award given the subject of the post), the numbers seem to suggest that the US contribution to pure mathematics is not as dominant as you might imagine: https://en.wikipedia.org/wiki/List_of_Fields_Medal_winners_b...

In any event, I think this is all getting rather silly. I was simply making the point that historically science in the US has benefited tremendously from having a large number of capable people that were trained within a different system. Where they were born is absolutely irrelevant. A certain W. von Braun was indeed an American, as were his 'major technological advances' that many in the US are rightly proud of, but he was very much a product of German science (I hope you don't find this point controversial).