Fish
Two. 1 to screw it in, and 1 to complain that it's not dark enough.
How many libertarians does it take to screw in a light-bulb? None. The market will take care of it.
Four - three to cut a hole in the roof and one to change the bulb.
22 one to screw it in 21 to shoot the bulb.
An Official.
Damn!
A fish