Tracking The Champions
Few sporting events capture the general public's attention like the Super Bowl. As much ritual tradition as NFL championship decider, the Super Bowl has become a uniquely American institution over its 46 years of existence.

Even though 18 of the NFL's 32 teams have won Super Bowls, there's surprisingly little turnover in championships throughout the NFL's history. More than half of the Super Bowl victors win a second championship within a few years of the first.
The average gap between arcs is 7.1 years, which includes six gaps of more than 10 years (from 27 total). More dramatic is the average time between a team's first Super Bowl win and its second, which is 5.8 years. Discounting the Baltimore/Indianapolis Colts, which had a gap of 36 years between its two titles, that figure drops to 2.8 years. Green Bay, Miami, Pittsburgh, and Denver won its first and second Super Bowls in consecutive years; the Patriots won their second two seasons after the first (picking up its third a year later), while the 49ers won their second three seasons after the first.
With four different winners in the past five seasons – five in the past six if the Patriots win on Sunday – there has been atypical turnover in titles recently, comparable only to 1999-2003, when the Broncos, Rams, Ravens, Patriots, and Bucs won, four of five for the first time. Still, the Giants are only four years removed from their last triumph, the Patriots seven from theirs. Multiple players remain from each franchise's previous title. While less dramatic than the heyday of the 1970s, 80s, and early 90s, dynasties still exist, no matter the NFL's current "parity, parity, parity" mantra.
Credit for this concept goes to soccer (football) infographics blogger On Goals Scored, who created this style of graphic for the English, Scottish, and Spanish and Portuguese leagues. If you have any interest in that sport, his website is required reading.

Ignoring the upcoming Giants-Patriots rerun, as we don't know the winner just yet, there have been five repeat Super Bowls. The team which was originally victorious won three of those five: the Steelers beat the Cowboys in Super Bowls X and XIII before losing 17 years later in Super Bowl XXX, the 49ers beat the Bengals twice in seven years, and the Cowboys beat the Bills in back-to-back Super Bowls during its mid-1990s dynasty.
Of those four different match-ups, only the Redskins beat the Dolphins at the second time of asking after losing in the first contest. And if the repeat contests take place less than 10 years after the first – as in the first two Steelers-Cowboys meetings, the 49ers-Bengals, and the Cowboys-Bills – the team that won the first also won the second. Coming four years after the Giants beat the Patriots in Super Bowl XLII, historical precedent bodes poorly for Brady, Belichick, and hordes of New Englanders on Sunday.