Education Week has an article about a recent study which attempts to compare 8th grade math and science proficiency percentage results for the various states in the US with proficiency results in other countries:

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Top-Achieving Nations Beat U.S. States in Math and Science

Students in the highest-performing U.S. states rank well below their peers in the world’s top-achieving countries in mathematics and science skill, according to a new
study. (link...)
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The EdWeek.org link requires free registration to access up to two articles per issue. The New York Times also picked up the story: (link...)

The study mentioned is available in PDF form at: (link...)

The saddest thing for me about the numbers in the study is that so few countries of the world (and states in the US) are rated at over 50% proficiency. Tennessee's 8th-grade numbers (23% "proficient" in math, 25% in science) given here are higher than the recently released study of adult proficiency (which said only about 13% of US adults were "proficient." See: (link...)