This may be what you're looking for: https://nces.ed.gov/programs/digest/d12/tables/dt12_349.asp
According to that table, women's bachelor's degrees in computer science:
* were low in the 1970's, about 15% average
* were higher in the 1980's, about 35% average
* declined in the 1990's to about 25-30%
* steadily declined from 27 to 17% in the 2000's