The warnings about skin cancer from too much sun don't seem to be getting through. Half of US adults under 30 say they have had a sunburn at least once in the previous year - about the same as a decade ago, according to a government survey released Thursday. In fact, the modest progress reported five years ago has been wiped out. Not only that, but women in their 20s are going to tanning salons almost twice a month on average. "I don't know that we're making any headway,'' said Dr. Len Lichtenfeld, the American Cancer Society's deputy chief medical officer. The study was conducted by the Centers for Disease Control and Prevention and was based on a 2010 survey of about 5,000 US adults ages 18 to 29. The share of those who said they had a sunburn in the preceding year dropped from about 51 percent in 2000 to 45 percent in 2005, then went back up to 50 percent in 2010. Researchers do not know for sure why the sunburn rate picked up again, said Dr. Marcus Plescia, director of the CDC's Division of Cancer Prevention and Control. The CDC found that more than one-third of those surveyed said they use sunscreen when they are out in the sun - a modest increase from 2005. But some specialists said the increasing rate of sunburns suggests many people are not putting on enough sunscreen or are not reapplying it adequately. -- ASSOCIATED PRESS