aeh, from the actual PISA report there is support for your statement although the comparison is to the top performing country being two years ahead in Maths than the top performing US state.
Key findings
• Among the 34 OECD countries, the United States performed below average in mathematics in 2012 and is ranked 27th (this is the best estimate, although the rank could be between 23 and 29 due to sampling and measurement error). Performance in reading and science are both close to the OECD average. The United States ranks 17 in reading, (range of ranks: 14 to 20) and 20 in science (range of ranks: 17 to 25). There has been no significant change in these performances over time.
• Mathematics scores for the top-performer, Shanghai-China, indicate a performance that is the equivalent of over two years of formal schooling ahead of those observed in Massachusetts, itself a strong-performing U.S.
• Just over one in four U.S. students do not reach the PISA baseline Level 2 of mathematics proficiency – a higher-than-OECD average proportion and one that hasn’t changed since 2003. At the opposite end of the proficiency scale, the U.S. has a below-average share of top performers.
