First of all, I am not saying the data is wrong, but it looks in the wrong place. I'll explain.
If the AVERAGE American takes a test and does more poorly than the AVERAGE European or the AVERAGE Zimbabwean, that is one thing. However, America is not run by its average people. The average people do the work, sure, but they are directed by the above-average, and I will tell you something about them. These people are the engineers, the scientists, the lawyers, the doctors, etc. While our average people don't stack up to the average people in other countries, our above-average people crush the above average people in pretty much every other place. Our engineers, our scientists, our doctors are light years better than the ones in most other countries. Why do you think so many come from abroad to study in our higher educational institutions? Because the education is GOOD, and among those above-average people in those schools there is an elite crop. It is they who run the country.
So these silly comparisons do not bother me. Our average people can be less average than the others, so long as we continue to excel among our elite.