While rates of unprotected sex among U.S. gay men are increasing, they are increasingly choosing partners of the same HIV status in order to reduce risk, according to studies by the San Francisco Department of Public Health and the University of California, San Francisco. However, the percentage of gay men who had unprotected sex with a partner of different or unknown HIV status rose from 9% in 1997 to 15% in 2002. While the studies focused on San Francisco, researchers believe the results have broader relevance.