It depends it think of how many people are left to act. If your utg, then the chance is higher than on the btn.

I think Phil Gordon had a easy calculation for this on his website.
I think it was something like take whatever PP (in this case KK) and multiply the number of players remaining by the number of over pairs (in this case 1) then divide by 2.

So 1 overpair better x lets say 5 players remaining div by 2 = 2.5%