OK, you are right. Seeing https://en.wikipedia.org/wiki/Science_and_technology_in_Iran... however also does not reveal anything about 70%:

The most popular in 2013 were social sciences (1.9 million students, of which 1.1 million women) and engineering (1.5 million, of which 373 415 women). Women also made up two-thirds of medical students.

Also, practicing researchers probably would be much better metric than students - if the student graduates as STEM major but then does nothing of the sort, then it's not really so relevant for participation anymore. If we had such situation in US, we would reasonably ask what is preventing those student from entering the labor market and consider situation where the distribution is 70/30 outside of university and 25/75 on the labor market abnormal.