I would expect that if X was 1 then there would almost never be a single image that contributes more than X%. So you'd have to make X=0.0001 or something, and

I would expect that if X was 1 then there would almost never be a single image that contributes more than X%. So you'd have to make X=0.0001 or something, and then what? Pay them all a fraction of a cent?