I would be interested in having some stats by education level and profession. From my current personal experience as a CS student, I would say it is easily above 50%.
Generally speaking, academic performance is inversely correlated with sex. In top universities the majority of students are virgins coming into university and a substantial percent (usually in the 25-50% range) are at graduation. Probably due to more time dedicated to study and career growth than relationships. Anecdotally, I've found that in tech and STEM more broadly rates of sex are lower - probably due to the overall gender imbalance means that the majority of people don't have potential partners in their primary social circles.
STEM is the worst social wise. You're correct that gender imbalances have a lot to do with this. There's also the fact that people who like STEM are generally social outcasts of some sort (nerds bullied in school, rarely the popular/cool kids).
