WAVA (now WMA) age grading is a method of comparing your running (and maybe other athletic?) performance across ages and genders. Most places describe it as being relative to the world record performance for a certain distance in your age/gender category (although not all).
However, I would like to know what it means to be further down the WAVA grading. Where is 0%? Is it the slowest performance ever recorded?
Is the range based on some sort of normal distribution? Is 50% WAVA some sort of average time for that age/gender category?