>So based on these tests, which country has the programmers that score the highest?

>In order to find out, we looked at each country’s average score across all domains

So it's taking the average of the country, not really looking at the best individual programmers. Considering the US had more entrants than China(which has 3x the population of the US), my guess is that there are many more mediocre devs from the US participating, which brings the average down.