Which is most commonly used, a bell trap, an S trap, a drum trap or a P trap?

In US, P trap most common, S traps illegal. Drum traps sometimes used for appearance and I think more often in Europe.

This question comes up often and usually from someone boning up for a test of some sort. Lisa, studying for a home inspectors test or what? Harold is correct but since S traps where made illegal but do not need to be removed I have no idea if there aren't millions of them out there. It's the P trap in our neck of the woods.