By the numbers: Same-sex marriage By By Caitlin Stark, CNN Library A same-sex couple celebrated a federal court's ruling in San Francisco, California in February 2012. Thirty-nine states have banned same-sex marriage Five states allow civil unions between same-sex couples, but not marriage Six states and the District of Columbia allow same-sex marriage According to the U.S. Census, there were 646,000 same-sex couple households in the U.S. in 2010. (CNN) -- Same-sex marriage was thrust into the political spotlight earlier this week after North Carolina voters approved a constitutional amendment that bans same-sex marriage in the state and President Barack Obama, who will accept the Democratic Party's nomination in North Carolina later this year, announced Wednesday that he personally supports same-sex marriage. Obama's announcement brought cheers from gay rights activists and Democratic allies and jeers from religious conservatives and some quarters of the GOP. Mitt Romney, the presumptive Republican presidential nominee, responded to all of the political chatter by reaffirming his belief that marriage should be defined as between a man and a woman and that states should be able to extend some rights short of marriage to same-sex couples. For this week's "By the numbers," we've complied some stats on same-sex marriage: 39 -- The number of U.S. states that have banned same-sex marriage. 5 -- The number of U.S. states that allow civil unions between same-sex couples, but not marriage. 6 -- The number of U.S. states that allow same-sex marriage, along with the District of Columbia. 2003 -- The year that the U.S. Supreme Court ruled that it is unconstitutional to criminalize sodomy. 2001 -- The year that the Netherlands made same-sex marriage legal, the first country in the world to so. 11 -- The number of countries worldwide where same-sex marriage is legal. 3.5% -- The approximate percentage of Americans identifying as lesbian, gay or bisexual, according to the Williams Institute at UCLA. 68% -- The percentage of Americans opposed to gay marriage in 1996, according to a Gallup poll. 48% -- The percentage of Americans opposed to gay marriage in 2012, according to a Gallup poll. 646,000 -- Number of same-sex couple households in the U.S. in 2010, according to the U.S. Census. 80.4% - The percentage growth of same-sex couple households in the U.S. between 2000 and 2010, according to the U.S. Census. 1.8% - The percentage of households in the District of Columbia comprised of same-sex couples, the highest in the nation. 7% - Approximate percentage of same-sex couple households that live in states that recognize same-sex marriage, as of 2010. 115,064 -- Number of same-sex couple households in the U.S. with children, according to the U.S. Census.