Since the late 1960s, PBS was one of the few sources for children's educational television programming in the U.S., and most other U.S. children's TV shows were violent and created for the purpose of selling toys. The Federal Communications Commission (FCC) ruled in 1997 that the commercial broadcast networks had to air educational children's programs for a minimum of three hours per week. The cable network Nickelodeon, which had been airing programs for six- to twelve-year-olds, was not legally bound by this legislation but complied with it anyway many years before the laws and regulations were passed.