Final answer:
There are 594,000 same-sex couple households in the United States, accounting for approximately 1.5% of total partner-headed households.
Step-by-step explanation:
According to the U.S. Census Bureau, there are 594,000 same-sex couple households in the United States, which is a 50 percent increase from 2000. This accounts for approximately 1.5 percent of the total partner-headed households in the country. The number of same-sex couples has been growing due to more people forming same-sex partnerships and the increasing social acceptance of LGBTQ individuals.