Heroin; coke; meth use

I'm a Psych Major doing a thesis on drug use and addiction with a focus
on heroin, coke and meth.   I've been doing some research and I'm
having difficulties getting info about:
- what is a typical amount of heroin/coke/meth used per day? ((IV
versus smoking
versus inhaling (if there is a difference)).
- what is the most you could use in a day?
- what is the range of how much could you use @[EMAIL PROTECTED]
 one time?
- how long does it take to get addicted?
- how much does a user typically buy @[EMAIL PROTECTED]
 one time?

Anything else you can think of that would be helpful would be very much

appreciated. 


Thanks in advance for your help.