I work where the staff is about 80% female, I know of one female that rides in pretty much all year, I ride pretty much all year and another guy rides in mostly fair weather. There are a couple more of both sexes, but they're more sporadic/seasonal.

The female that rides a lot puts me to shame, in all honesty, but as the numbers go I'd say it's usually a 66/33 split for men, with an occasional 60/40 or 70/30 male split.

It's nice to know that others in the office do ride though, as small as the number is. Ever since I started bringing my bike into my office, it's been noticed and we're getting a bike rack in our new building, and some showers. Yay.