According to the Dutch National Drugs Monitor, produced by the Utrecht-based Trimbos Institute, the number of people addicted to cannabis tripled between 2000 and 2010. In 2000, 3,534 people were treated for cannabis addiction. Nearly 11 000 were treated in 2010. 40% were under the age of 25.The full report, with a summary in English (pp. 29-42), is available here.