<P> About 17% of D.C. residents were age 18 or younger in 2010; lower than the U.S. average of 24% . However, at 34 years old, the District had the lowest median age compared to the 50 states . As of 2010, there were an estimated 81,734 immigrants living in Washington, D.C. Major sources of immigration include El Salvador, Vietnam, and Ethiopia, with a concentration of Salvadorans in the Mount Pleasant neighborhood . </P> <P> Researchers found that there were 4,822 same - sex couples in the District of Columbia in 2010; about 2% of total households . Legislation authorizing same - sex marriage passed in 2009 and the District began issuing marriage licenses to same - sex couples in March 2010 . </P> <P> A 2007 report found that about one - third of District residents were functionally illiterate, compared to a national rate of about one in five . This is attributed in part to immigrants who are not proficient in English . As of 2011, 85% of D.C. residents age 5 and older spoke English at home as a primary language . Half of residents had at least a four - year college degree in 2006 . D.C. residents had a personal income per capita of $55,755; higher than any of the 50 states . However, 19% of residents were below the poverty level in 2005, higher than any state except Mississippi . </P> <P> Of the District's population, 17% is Baptist, 13% is Catholic, 6% is evangelical Protestant, 4% is Methodist, 3% is Episcopalian / Anglican, 3% is Jewish, 2% is Eastern Orthodox, 1% is Pentecostal, 1% is Buddhist, 1% is Adventist, 1% is Lutheran, 1% is Muslim, 1% is Presbyterian, 1% is Mormon, and 1% is Hindu . </P>

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