[refurb]

There is no qualitative explanation as to why that should be true.

I think there are plenty of qualitative explanations especially if look back a few decades (since most CEOs are in their 50s).

Women didn't obtain the name number of university degrees as men until recently. Women often step out of the workforce in order to care for family, etc, etc.

All of these would explain where there would be a smaller pool of qualified women to take a CEO role.