On my travels once I met a little man - or was it a woman with a curly 'tash and leather shorts? - who told me the formula (get a pencil and paper):
For every city in the canton = three large holes 1/2 inch diameter each;
For every town " " = three medium holes 1/4 dia. each;
Per village " " = four small holes 1/8 dia. each;
Per farm (10+ cows) " " = five smaller holes 1/16 dia. each;
Per farm (less cows) " " = five pin-holes 1/32 dia. each.
We made our farewells and he/she went off yodelling (translation of message in the yodel: "one more, one more).
Whaddya mean you don't believe it?!