I don't doubt it, but I had to wonder where they got the hard data. They didn't. This note was on the site:

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*It bears mentioning that Lynn's studies, while comprehensive, tend to spark considerable debate. Some researchers dispute the techniques Lynn employs to calculate estimates when hard data is lacking. Others claim Lynn, an unabashed eugenicist, misinterprets his data to support conclusions that are both scientifically inaccurate and supportive of white supremacy.

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Just wondering where they came up with everyone's IQ score to figure the average per country. Regardless, the U.S. is getting dumber.