Analysis of 30 years of SAT and ACT tests administered to the top 5% of U.S. 7th graders has found that the ratio of 7th graders scoring 700 or above on the SAT-math has dropped from about 13 boys to 1 girl to about 4 boys to 1 girl. The ratio dropped dramatically between 1981 and 1995, and has remained relatively stable since then. The top scores on scientific reasoning, a relatively new section of the ACT that was not included in the original study, show a similar ratio of boys to girls.
(Submitted). Sex differences in the right tail of cognitive abilities: A 30 year examination.
Intelligence. 38(4), 412 - 423.