Then the stats for "other drug use" should come to more than half of the figures for pot use. If they don't someone is lying.
Didn't you see the poll of youth who were asked if they lied on polls about drug use/drinking/smoking? Of course people lie about such things. Only the idiots brag about their drug abuse. You generaly don't have to ask them anyways, you can spot them a mile away.
Not if they go on to other drugs then die. Or quit.