How many marriages in the US are interracial?

According to the United States Census Bureau, the number of interracially married couples has increased from 310,000 in 1970 to 651,000 in 1980, to 964,000 in 1990, to 1,464,000 in 2000 and to 2,340,000 in 2008; accounting for 0.7%, 1.3%, 1.8%, 2.6% and 3.9% of the total number of married couples in those years,