Since I have some time, some interesting Super Bowl stats:

• The NFC/pre-merger NFL and the AFC/AFL are now tied in Super Bowls:  25 each after the merger, 2 each before it.  27-27
• The first even (by my definition) competitive Super Bowl (within one score in the fourth quarter) was Super Bowl V, won with a field goal at nine seconds left for the Colts by Jim O'Brien.
• Cliffhangers:  V (FG 0:05), XXIII (TD SF 0:34), XXXII (TD DEN 1:45), XLII (TD NYG 0:35)
• Within one score, not Cliffhanger: VII, XLV, XLVII
• Competitive, neither:  IX, XIV, XVII, XXVIII, XXX, XL, XLI, XLIV, 50, LIII, LIV
• Last Chance Miss:  X (end zone pass), XIII (onside), XIV (onside), XXV (Norwood wide right), XXXIX (onside, though PHI got another chance and did nothing -- still qualifies under my definition), XLIX (NE's winning TD at 2:02, but SEA decided to throw the ball when they had Marshawn Lynch TV smashed), LII (Hail Mary try at the gun)
• Cliffhanger AND Last Chance Miss:  XXXIV (TD STL 1:54, One Yard Short on the tie), XLIII (TD PIT to win 0:35, fumble on Hail Mary attempt ARI 0:05)
• Double Cliffhanger:  XXXVI (TD STL to tie 1:30, Seven Second FG to "win" at the gun NE), XXXVIII (TD CAR to tie 1:08, NE FG to win 0:04), XLVI (TD NYG 0:57, Hail Mary failed in the air at the gun NE), LI (NE 0:58 TD + 2 to tie, NE wins in OT)
• XXXVIII was quite the NFL production.  Four lead-changing to tying scores in the last seven minutes.

So, in summary:

• Nine Cliffhangers, with seven Cliffhangers of some kind since Super Bowl XXXII.
• Only 18 of the 54 Super Bowls have been decided within one score, and there have been non-competitive games in half the Super Bowls.