Note that these add up to more than 100% because they are cumulative; e.g. it is assumed that all people with doctorates also have undergraduate and high school degrees, and are thus counted twice in the "lower" categories. Age 25 is used rather than age 18 because there are few people aged 18 or over with advanced degrees. "Educational Attainment in the United States: 2018". U.S. Census Bureau. Retrieved 23 June 2018. Percentages are calculated based on census data by counting people that had attained that level or higher.
