Assuming the effect is consistent and did not hit any DEX soft cap, each 1 point of DEX reduced the miss rate by 0.0532%
This kind of thing is rediculous. I'd rather we go to a non-assigned stat system where each point is controlled by your Rank/Level/Gear/Skills and not your whimsical self and then each singular point of a stat increase effectiveness at the least 1.5%. .0532% is nothing :/