Among people age 12 or older, the percentage with a past year marijuana use disorder was 1.8% in 2002 (or 4.3 million people) and 2019 (or 4.8 million people) but showed declines in some years. Key Substance Use and Mental Health Indicators in the United States: Results from the 2019 National Survey on Drug Use and Health. SAMHSA. Published September 2020.