Since the 2010-11 school year up to the 2020-21 cohort, Connecticut's statewide four-year graduation rate increased 6.9 percentage points, from 82.7% to 89.6%, according to state data.

The median graduation rate in 2010 was 89.6% compared to 93.8% in 2020.

The school districts with the consistently lowest graduation rates were two school districts operated by state agencies and one charter school.

Unified School District #1, which serves incarcerated individuals and is headed by the Department of Correction, had its graduation rate increase from 1.4% to 3.8% but had suppressed data in the school years starting in 2012, 2013 and 2016 to ensure confidentiality.

Unified School District #2, which serves children residing in Department of Children and Families (DCF) facilities, dropped from a 30% graduation rate to 28.6% in the 2016-17 school year. Graduation rates for the rest of the school years were not available because DCF suppressed the data for confidentiality.

Stamford Academy District, a charter school, had its graduation rates range from 36.4% in the 2010-11 school year up to 50% in the 2019-20 school year. Data for the 2020 school year was suppressed for confidentiality.

The public school districts with the lowest graduation rates throughout the decade were in Hartford, New Britain and Bridgeport, while the highest were in Weston, Westport and New Canaan.

The biggest improvements were by the charter Amistad Academy District, which saw a 34.8 percentage point increase, and New Britain School District, which went from 51.3% in the 2010-11 school year to 78.7% in the 2020-21 school year, a 27.4 percentage point increase.

Read more: CT has changed in the last decade. Here are 10 charts that show how