Halftime shows are a tradition during American football games at all levels of competition. Entertainment during the Super Bowl, the annual championship game of the National Football League (NFL), represents a fundamental link to pop culture, which helps broaden the television audience and nationwide interest. Prior to the early 1990s, the halftime show featured university marching bands (the Grambling State University Marching Band has performed at the most Super Bowl halftime shows, featuring in six shows including at least one per decade from the 1960s to 1990), drill teams, and other performance ensembles such as Up with People. In the 90s, the halftime show began to feature major hit musicians, beginning with Super Bowl XXV (1991) with New Kids on the Block. In an effort to boost the prominence of the halftime show to increase viewer interest, Super Bowl XXVII (1993) featured a headlining performance by Michael Jackson.