Who knew there was such appetite for 1990s tween sitcoms? It seems like TeenNick stumbled onto a gold mine with its retro The 90s Are All That 12 AM-2 AM block, which launched Monday, drawing some 555,000 total viewers for the first night, a 114% time-slot improvement vs. last year. The gains were even more impressive in the younger demos: 1.3/417,000 among adults 12-24, up +225%, and 0.6/229,000 in adults 18-34, up +500%. In those demos, the reruns of Nickelodeon’s Kenan & Kel (from 1995), All That (1996), Doug (1991) and Clarissa Explains It All (1992) bested most network late-night shows. On Twitter, TeenNick had eight of nine trending topics worldwide during the block’s premiere.