Radio stations in the United States often broadcast popular music. Each music station has a format, or a category of songs to be played; these are generally similar to but not the same as ordinary generic classification. Many radio stations in the United States are locally owned and operated, and may offer an eclectic assortment of recordings; many other stations are owned by large companies like Clear Channel, and are generally formatted on smaller, more repetitive playlists. Commercial sales of recordings are tracked by "Billboard" magazine, which compiles a number of music charts for various fields of recorded music sales. The "Billboard" Hot 100 is the top pop music chart for singles, a recording consisting of a handful of songs; longer pop recordings are albums, and are tracked by the "Billboard" 200. Though recorded music is commonplace in American homes, many of the music industry's revenue comes from a small number of devotees; for example, 62% of album sales come from less than 25% of the music-buying audience. Total CD sales in the United States topped 705 million units sold in 2005, and singles sales just under three million.