Global Estimate of Prevalence of Injection Drug Use
"Updating the previous global estimates, the United Nations Office on Drugs and Crime (UNODC) estimates that in 2011 a total of 14.0 million (range: 11.2 million to 22.0 million) people injected drugs worldwide, which corresponds to 0.31 per cent (range: 0.24-0.48 per cent) of the population aged 15-64.14 The current global estimates are lower than the previous ones of 15.9 million people, and primarily reflect the fact that many countries have revised their earlier estimates downward, based on behavioural surveillance data. However, many countries have also reported an increase in the prevalence of injecting drug use and in the number of people who inject drugs.
"Changes over time in national, regional and global estimates of injecting drug use may result from a number of factors, such as improvements in the methodology or coverage of behavioural surveillance (e.g., Georgia, Italy and South Africa), additional countries undertaking behavioural surveillance for the first time (Kenya and Seychelles) or changes in patterns of drug use, including injecting drug use (Australia and Brazil). Such factors have contributed to the overall reduced global estimates of people who inject drugs. Notable increases in the estimated number of people who inject drugs have been reported from Pakistan, the Russian Federation and Viet Nam, while countries reporting a considerable reduction include Brazil, Indonesia, South Africa, Thailand and the United States."
UNODC, World Drug Report 2013 (United Nations publication, Sales No. E.13.XI.6), p. 3.