Well, countries where people have been taking exams for hundreds of years are at the top (China, South Korea).
Not to say the IQ measures leadership or creative skills.
I’m happy not being in those nations. Tests only show so much.
I suspect one factor in the Asian countries the difficulty of the written language — and of course the culture that goes with it.
I think another survey is needed to measure adaptability. Very important quality where I think Americans probably rank high.