"Sometimes, in the smaller market weather areas, you'll notice that it's always even multiples of 20%. Those bureaus only get five cows."

So is it possible that in some really large 'market weather areas' (whatever that means) they're given a hundred cows... That should enable them to predict say, a seventy-three percent chance of rain... OTOH, if in some really small market weather areas, they're given only three cows, they should be able to predict one in three chance of rain...

Just wanderin'...