Heres some more for you
Q:
Is marijuana dangerous?
A: Marijuana users also have the same or lower incidence of murders and highway deaths and accidents than the general non-marijuana- using population as a whole. Crancer Study, UCLA: U.S. funded ($6 million) First and Second Jamaican studies, 1968 to 1974; Costa Rican Studies, 1980 to 1982; et al.
Drug War Fact
In 2000, there were 1,579,566 drug arrests in the US. Of those, 46.5 percent -- 734,497 arrests -- were for marijuana. There were 646,042 arrests for simple possession of marijuana in 2000.
Q:
Isn't today's marijuana much more potent than it was in the Sixties?
A: Yes, it usually is. The good news is that is actually better for you because there is more THC and less excess "material". The excess material is what damages your lungs. Also being more potent you have to smoke less to achieve the same result.
Here is a Link for more information and a killer site..