In 2001, Portugal became the first European country to officially abolish all criminal penalties for personal possession of drugs, including marijuana, cocaine, heroin and methamphetamines.
[A] paper, published by Cato in April 2011, found that in the five years after personal possession was decriminalized, illegal drug use among teens in Portugal declined and rates of new HIV infections caused by sharing of dirty needles dropped, while the number of people seeking treatment for drug addiction more than doubled.
Dropped significantly - deaths related to heroin dropped by 50%.