I don't know how much things have changed, but when I was being schooled in Poland, the standards were very very high, especially when it comes to math. I moved to West Germany and found the math there to be a joke. I struggled in Poland and excelled in Germany. Moved to Canada and found the math in school here even more of a joke. My aunt teaches high school math in Toronto and agrees with me. Looking at the above graph, I see that Poland is higher than the US but lower than Canada, even in the field of math. I guess the standards have changed? Either way, if American standards are lower than Poland's and Canada's, then they can't be that great.