I'm always fascinated at how common it is for people (almost universally cynics from outside the US) to try to discredit the US winning this competition by proclaiming that the participants aren't really Americans, because they're of some other ethnicity than white. It usually goes like this: 'well, they're mostly Asians, so it doesn't count.' I saw it constantly with the US winning last year's International Math Olympiad, and I'm seeing it again on various forums this year. Often it comes in stealth form, they'll ask intentionally leading questions about where the competitors were educated, or where they were born, trying to avoid being too blatant about their racism and or anti-US cynicism. Some people just can't stand for the US to do well in anything.