American Top 40 quickly became one of the most popular syndicated radio shows in the country and then around the world. By 1986 the show was featured on more than 1,000 radio stations in 50 countries around the world as well as Armed Forces Radio and the Voice of America. American Top 40 spawned a television spin-off, America's Top 10, that ran from 1980 through 1990 and featured Casey Kasem counting down the week's top 10 hits and playing music videos. Check out this video for one of the biggest tunes of 1975.