prime time dramas aimed at younger audiences that became quick hits, which, in addition to Beverly Hills, 90210, included its adult-focused spin-off Melrose Place (which initially had a mediocre ratings performance, before viewership rose significantly midway through its first season following Heather Locklear's addition to the cast) and family drama Party of Five. The early and mid-1990s also saw the network launch several series aimed at a black audience, which, in addition to Martin, included the sitcom Living Single and police procedural New York Undercover. Luring the NFL and affiliation switches Despite having a few successful shows like the science fiction drama The X-Files, Fox still lacked credibility among viewers. Even those working in television thought of the network as "the one that has that cartoon show" (The Simpsons). More than 85% of affiliates in 1993 were UHF stations. Fox became a viable competitor to the older networks when it won broadcast television rights to the National Football League away from CBS. In December 1993, Fox signed a contract with the NFL to televise games from the National Football Conference—which had been airing its games on CBS since 1956—starting with the 1994 season. The initial four-year contract, which Fox bid $1.58 billion to obtain—while CBS offered $295 million per year to retain the rights—also included the exclusive U.S. television rights to Super Bowl XXXI in 1997. The network also lured Pat Summerall, John Madden, Dick Stockton, Matt Millen, James Brown, Terry Bradshaw, and behind-the-scenes production personnel, from CBS Sports to staff its NFL coverage. Shortly afterward, News Corporation began striking affiliation deals with, and later purchasing, more television station groups. On May 23, 1994, Fox agreed to purchase a 20% stake in New World Communications, a television and film production company controlled by investor Ronald Perelman that had just recently entered into broadcasting through its 1993 purchase of seven stations owned by SCI Television. As a result of Fox acquiring a 20% minority interest in the company, New World signed an agreement to switch the affiliations of twelve stations (eight CBS affiliates, three ABC affiliates [ two of which were subsequently placed in a blind trust and then sold directly to Fox due to conflicts with FCC ownership rules], and one NBC affiliate) that it had either already owned outright or was in the process of acquiring from Citicasters and Argyle Communications at the time to Fox starting in September