"The number of problem drug users estimated at national level varies from 222,000 (multiplier applied to arrest data) to 340,000 (multivariate indicator method), corresponding to a prevalence of 5.5 per thousand and 8.4 per thousand, respectively, depending on the method employed. The multiplier method applied to treatment data gives an intermediate prevalence of 7.5 per thousand. Estimates based on arrest data are lower than the other two estimates, especially for those obtained with the multiplier method, with no cross-checking between confidence intervals. In 2006, the range of values adopted at national level, i.e. 210,000 to 250,000 users, corresponded to the overlap zone of confidence intervals calculated for each estimation method. Adoption of the same principle for the 2011 data led to disgard the multiplier method applied to arrests. The only estimates retained were based on treatment data and the multivariate indicator. A rather large range in values was thus obtained, namely 275,000 to 360,000 problem drug users. The upper and lower prevalence limits associated with these estimates are 7 per thousand and 9 per thousand. This result places France on an upper average ranking in terms of European Union statistics, with prevalences rounding similar levels to that observed in western European countries such as Italy, Spain and the UK, although markedly superior to Portugal and Germany."

Source

l'Observatoire francais des drogues et des toxicomanies (OFDT), "2012 National Report (2011 data) to the EMCDDA by the Reitox National Focal Point: France: New Development, Trends and in-depth information on selected issues (Saint-Denis, France: OFDT, 2012), p. 62.
http://www.ofdt.fr/BDD/public…