Washington Redskins offensive lineman Jon Jansen said that "maybe 15, 20 percent" of NFL players use performance-enhancing drugs and that their use is "on the rise now" because of human growth hormone treatments that are undetectable by the NFL's testing method. "You know guys that are doing it," Jansen said on the HBO program "Costas Now" that aired Wednesday night. "You know that they're cheating and you know that they're trying to get by with something."