How can art museums make their collections more diverse?

African-American artists like Kerry James Marshall, Amy Sherald, and Kehinde Wiley are becoming more visible. But those gains are only recent. If you look at the past decade, works by black artists are just 2.3 percent of all acquisitions at dozens of prominent museums around the country. That’s according to recent data-crunching by Artnet News and a podcast called “In Other Words.” So what can be done about that low percentage?