LSD: 1 star (if I remember correctly)
Canabis: 1 star
Cigarets: 2 stars (notice how people have a hard time to stop smoking)
Alcohol: 3 stars
Cocaine: 3 stars
Heroin: 6 stars
In my mind, if you try heroin once, you're addicted. Is that close to be correct? Because if it's correct, then the less people try it, the less there's addicts.