I could not find any American
studests on the list.
How about you explain how you measure reading skills in different languages? How many American students have English as a second language? We don't test in Spanish, Arabic, or any of the other languages that my students used in their home every day. Back when they were doing the TIMSS tests, Germany pulled out of the testing program because their students did so poorly, and they only tested the upper division of their students. They felt the test were biased against their students.