It's not publicized, but, did you notice that the weather forecast always gives the percent chance of rain in even multiples of 10%? You never hear that there's a one in three chance of rain. The local weather bureaus are each given 10 cows and they count the number that are lying down to determine the chance of rain. Sometimes, in the smaller market weather areas, you'll notice that it's always even multiples of 20%. Those bureaus only get five cows.