More post-secondary education is key to improving a local economy, according to Milkin Institute Chief Research Officer Ross DeVol. DeVol said a solid economic plan for Tucson should include efforts to retain as many University of Arizona graduates as possible. Retention of college graduates could help attract employers and increase the number of startup businesses in the local economy. A Milkin Institute study found Tucson ranks 90th in the country among major metropolitan areas for percentage of workers with a bachelor's degree or higher. It ranked 62nd in 1990.