Since the start of the Drug War, prices are down, numbers and ages of users are up, availability is up, supply is up, purity is up and there are approximately 14 million people in the U.S. who are willingly admit to using them regularly.
What were the numbers before the Drug War?
I believe you are using a poor comparison to prove your point. By comparing the drug culture of the 1920's and the drug culture of 2002 in the midst of the WOD and saying "See what prohibition has done?" you are ignoring a host of cultural factors that are the reasons for the stark rise in drug use.
For one thing, a generation emerged in the 1960's that was determinded to destroy itself. The legality/illegality of drugs had little to do with it.
I hope you are not trying to suggest that, if we made drugs legal today, we would return to the cultural state of the turn of the 20th century.