As of 2007, about one-third of Washington, D.C., residents were functionally illiterate, greater than the national rate of about one-fifth. The city's relatively high illiteracy rate is attributed partly to immigrants who are not proficient in English. , 85% of D.C. residents age5 and older spoke English at home as a primary language. Half of residents had at least a four-year college degree in 2006. In 2017, the median household income in D.C. was $77,649; also in 2017, D.C. residents had a personal income per capita of $50,832 (higher than any of the 50 states). However, 19% of residents were below the poverty level in 2005, higher than any state except Mississippi. In 2019, the poverty rate stood at 14.7%.