The U.S. Census Bureau's news release is linked below.
U.S. Census Bureau: 21% of Married Couples Have at Least One Member of Foreign Nativity
"The U.S. Census Bureau reported [September 5, 2013] that 11.4 million married-couple households, or 21 percent of all married-couple households in America in 2011, had at least one spouse born in another country. About 13 percent (7.3 million) of households had two foreign-born spouses, and 7 percent (4.1 million) had one native-born and one foreign-born spouse."
---U.S. Census Bureau