In this video from 9:37 to 10:14, Karen Straughan mentions a study of 53 countries that showed that the more prosperous a country is, the more gendered choices of field of study and profession become. She also says that Norway has employed massive government-funded initiatives to get more women into engineering, which have only yielded a 2-3% improvement which doesn't persist when the programs are scaled down.

Can anyone find these studies? Or any other study on the same or similar subjects?