The flagship set from Topps has been produced every year since 1952. The sets were originally produced and distributed in individual packs in multiple series per year, some more scarce than others. As the hobby matured and the sports card industry grew, Topps changed their model, improving the quality of the cards, releasing factory sets in addition to packs, and removing the gum from the packs beginning in 1992 with 1992 Topps.