You can skip the email request (click "No Thanks") and it starts the download for the "Women in IT: The Facts" report.

EDIT: Here's the pertinent section. They are saying they leave the field, not company, mid-career:

"In 2003, only one-third of women with a computer science bachelor’s degree were still employed in a science, engineering, or technical (SET) job two years after graduation. According to a study by the Center for Work-Life Policy, 74 percent of women in technology report “loving their work,” yet these women leave their careers at a staggering rate: 56 percent of technical women leave at the “mid-level” point just when the loss of their talent is most costly to companies. This is more than double the quit rate for men. It is also higher than the quit rate for women in science and engineering."