The all-male board is officially a thing of the S&P 500’s past.

Copart Inc., the last company in the index without a female director, appointed CyrusOne CFO Diane Morefield to its board of directors this week. Earlier this year, Skechers and TripAdvisor Inc also added women.

The final stretch of progress has been slow. In 2000, about 86% of S&P 500 companies had at least one women on their board according to Spencer Stuart. The last 14% of companies have taken almost 20 years to close the gap.

Gender balance at the board level has long been a focus for activist investors, but the cause got new momentum with State Street Corp.’s Fearless Girl campaign in 2017. Last year, California instituted something like a quota system for companies headquartered in the state. New Jersey has a similar bill pending.

Shareholder advocates still say it is ideal to have at least three female directors. Big investors like BlackRock Inc. and State Street say board diversity is linked to better returns and in the past few years have begun to ask male-dominated boards to explain themselves.

This article was provided by Bloomberg News.