Compared with the state’s 66 other counties, Chester County is home to the highest percentage of residents who have graduated from college, according to data analysis from Stacker.

Stacker compiled the list using U.S. Census Bureau data. It ranked counties based on the highest percentage of the population, aged 25 and older, with at least a bachelor’s degree.

Chester County ranked first; 53 percent of its adult population has a degree.

Specifically, 21.5 percent of the population has a graduate or professional degree. Their pursuit of an advanced degree earns them a median annual income of $96,404.

The share of the population with a bachelor’s degree ($69,676 median earnings) is 31.5 percent, while 19.8 percent of residents have some college or an associate’s degree ($45,085 median earnings).

Meanwhile, 20.8 percent have only graduated from high school and have median earnings of $38,682.

Finally, the county has just 6.4 percent of residents who have less than a high-school diploma. Their median earnings are $26,063.

All of Philadelphia’s collar counties ranked in the Top 10: Montgomery County came in second, Bucks County ranked fifth, and Delaware County placed sixth.

Read more about each county’s levels of continuing education at Stacker.