But in one occupation — one at the very tiptop of Corporate America — the median woman has consistently earned more than the median man. It’s the corner office of the country’s largest public companies: chief executives of S&P 500 corporations.

A new analysis of the largest public U.S. companies by the Associated Press and Equilar, the executive pay and corporate governance research firm, found that the median female CEO made $13.1 million in 2016, compared with $11.4 million for the median male CEO.

“I don’t think there’s any one definitive reason we can say this is happening,” said Dan Marcec, Equilar’s director of content. “It could just be a matter that these individuals happen to be running some of the more well-performing companies, and that’s reflected in their compensation.”

Whatever the reason, it’s been happening repeatedly — and for a while.