In the US 18% engineering students at undergraduate level were female as of 2012 [0].

In fact, apparently in Iran almost 70% of science graduates are female [1], making the courses less diverse in terms of gender than the US, which I believe is closer to 50/50 for "science" collectively (can't find data).

[0] http://chronicle.com/article/In-Terms-of-Gender/135304/

[1] http://contexts.org/articles/spring-2011/what-gender-is-scie...