The most important aspect to consider when looking at statistics is not the % of winners which fit the given criteria but how this % relates to the % of starters that fit the criteria.

eg. last start winners (the numbers are made up!)

25% winners are last start winners
but 30% runners are last start winners

This means that last start winners actually won less races than would be expected (30%)

Here is a list of the % of starters that carried the given weight.

<52kg 1.5%
52-54.5 59.5%
55-59 34.6%
>59kg 1.9%

This is from races run everywhere by all classes (including jumpers) which account for the majority of weights >61kgs.

The challenge is to post the most accurate figures as to the % of winners that fall into each category.