One year while I was getting my physics degree, I looked through the roster of the ~100 students in the major and found that a randomly-selected one was more likely to be named Andrew, Ryan, or Austin than be a woman.

My grad school friends, who all came to AGU in SF from the UK one year, sat on the floor at the entrance to the poster hall and counted people walking in. They classified three groups of people, whose numbers were approximately equal - men, bearded men, and women.