If you’re a Boston sports fan over the age of 30, it may be emotionally difficult for you to think of your teams as successful. (Disclosure: I am, and it is.) But the facts are pretty clear: Boston is America’s most successful modern sports town.

Its teams in the four major pro sports leagues have won championships in an impressive 10 percent of the seasons they’ve played over the last 50 years, the highest share for any city with at least two teams. In the 1960s and 1970s, that success came exclusively from the Celtics. But since 2008, all four teams — Celtics, Bruins, Patriots and Red Sox — have won a title.

Pittsburgh is second by this 50-year measure, at 8 percent, and Los Angeles third at 6.3 percent. If we expand the universe to include cities with only one team, San Antonio narrowly beats Boston, with titles in 10.6 percent of seasons.