 Complete the following phrase:  The 1972 Dolphins capped off the only perfect season in NFL history with their victory in Super Bowl VII. The only teams with multiple Super Bowl appearances and no losses are the Baltimore Ravens and the Tampa Bay Buccaneers, both having achieved a  Super Bowl record. Four current NFL teams have never appeared in a Super Bowl, including franchises that have relocated or been renamed: the Cleveland Browns, Detroit Lions, Jacksonville Jaguars, and Houston Texans, though both the Browns 1950, 1954, 1955, 1964 and Lions 1935, 1952, 1953, 