the 1.9% figure is for all horses carrying 59.5kgs or more (>59) it is for all races run by thoroughbreds (as posted earlier).

Rob, no I am not going to post the winning percentages to match the runners % I posted earlier.

The challenge was for you to try to figure it out (provoke thought). I will offer some guidance as to if you are on the right track.
5% is significantly higher.

I just picked a random day Dec 1 2001 to illustrate my point. @ the metros B,S,M,A 366 horses went around in 32 races, 5 carried 59.5kg or more. This is 5/366 = 1.37% of these 0 won, 0/32 = 0%

For those who think 1.9% is too low consider this. On your average 8 race card say there are 100 runners (12.5/race) this means there should be 1.9 horses weighted to carry 59.5kgs or more. There is probably only going to be 1 horse per race weighted this highly so that's two races gone. Say a couple of set weights races another two gone and the other four races are just your average handicap with a top weight around 56-58kg.

A further point: the horses that win with big weights are often horses racing in the country that are significantly better than their opposition (eg Century Kid @ Wagga)