"Some 4.3 percent of Americans have been dependent on marijuana, as defined in the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition, Text Revision (DSM-IV-TR; American Psychiatric Association, 2000), at some time in their lives. Marijuana produces dependence less readily than most other illicit drugs. Some 9 percent of those who try marijuana develop dependence compared to, for example, 15 percent of people who try cocaine and 24 percent of those who try heroin. However, because so many people use marijuana, cannabis dependence is twice as prevalent as dependence on any other illicit psychoactive substance (cocaine, 1.8 percent; heroin, 0.7 percent; Anthony and Helzer, 1991; Anthony, Warner, and Kessler, 1994)."
Budney A, Roffman R, Stephens R, Walker D. Marijuana dependence and its treatment. Addiction Science and Clinical Practice. 2007;4(1):4–16.