Rankings and Percentiles?

I guess I am confused on how the ranking percentiles truly work. Today we did BWL and before the fights I looked at what the 99 percentile rankings were. My example would be on Ebonroc as a Holy Paladin you need 241.34 HPS to be at the 99 percentile. Today I did 258 on the fight but it ranked me at 98%.

How do these rankings work and am I looking at the numbers wrong or did the bar get raised and just hasn’t been updated yet?