NEW YORK - Experimentation with human growth hormone by America's teens more than doubled in the past year, as more young people looked to drugs to boost their athletic performance and improve their looks, according to a new, large-scale national survey. In a confidential 2013 survey of 3,705 high school students, being released Wednesday by the Partnership for Drug-Free Kids, 11 percent reported using synthetic HGH at least once - up from about 5 percent in the four preceding annual surveys. Travis Tygart, CEO of the U.S.