There's a lot of data on this page http://www.womenintechnology.org/witef/resources It's a bit scattered but here are some parts I found interesting:

Women in the mathematics, and engineering have long been underrepresented in tenured and full professor positions but overrepresented in untenured and junior faculty positions, even after controlling for publication productivity and institutional affiliation... Today, women faculty in science and engineering are still promoted more slowly and receive fewer honors and leadership positions.

77 percent say significant numbers of women and underrepresented minorities are missing from the U.S. STEM workforce today because they were not identified, encouraged or nurtured to pursue STEM studies early on.

"Persistent stereotypes that say STEM isn’t for girls or minorities" is one of the top causes of under-representation in STEM.

I didnt even know who my professors where or would be when I enrolled in university, are you suggesting women dont enroll in IT because there arent female professors?

The data isn't about when you enroll but when you graduate.

I am sorry if this isnt clear but you are talking about professors at universities and people who are enrolling I dont see the link?

Well, many college students don't settle on a degree for the first year or two and it's pretty normal to switch majors. If you get through a few courses and there are no women role models in the department, I would guess that more women than men would switch to something else.

I would guess Now I understand what your saying.