Estimated Number and Prevalence of People Who Inject Drugs

"The joint UNODC/World Health Organization (WHO)/Joint United Nations Programme on HIV/AIDS (UNAIDS)/World Bank estimate for the number of people worldwide who injected drugs in 2015 is 11.8 million (range: 8.6 to 17.4 million), corresponding to 0.25 per cent (range: 0.18 to 0.36 per cent) of the population aged 15-64 years. This estimate is based on the reporting of injecting drug use from 107 countries, covering 89 per cent of the global population aged 15-64 years.

"Subregions where the prevalence of injecting drug use is above the global average are Eastern and South-Eastern Europe, Central Asia and Transcaucasia, North America, Oceania and South-West Asia. More than half (53 per cent) of PWID worldwide reside in just four countries (China, Pakistan, Russian Federation and United States)."

Source: 

United Nations Office on Drugs and Crime, World Drug Report 2017 (ISBN: 978-92-1-148291-1, eISBN: 978-92-1-060623-3, United Nations publication, Sales No. E.17.XI.6). Booklet Two: Global Overview of Drug Demand and Supply: Latest trends, cross-cutting issues, p. 19.
https://www.unodc.org/wdr2017/
https://www.unodc.org/wdr2017/...