a lack of a commercially available single. While this practice did not end, in the Billboard issue dated December 5, 1998, policy was revised to allow "airplay-only" songs to chart on the Hot 100. Number-one airplay hits See also 1990s in music List of Hot 100 number-one singles of the 1990s (U.S.) Notes and references Additional sources Whitburn, Joel. The Billboard Book of Top 40 Hits. (2004) Billboard Biz United States Hot 100 Airplay Billboard charts Lists of number-one songs in the United States 1990s in American music