Interesting numbers. Yes, in raw numbers the #1 seeds have won the most Super Bowls since 1999 (if your numbers are accurate, which I assume they are).
But in terms of percentages, the #1 seeds have the worst record of winning.
#1 - 8 of 22, or 36%
#2 - 5 of 10, or 50%
#3 - 1 of 2, or 50%
#4 - 3 of 7, or 43%
#5 - 2 of 2, or 100%
#6 - 2 of 2, or 100%