Explanatory notes

The figures show a simplified graphical presentation of the patterns of prevalence of drug use for each country (left-hand figure), and the position of the country in an overall rating of reporting countries (right-hand figure).

The diagrams summarise the most recent information over the past 5 years provided to the EMCDDA. In some cases data are not available for the country and in other cases, where alternative estimates of prevalence are available for the same year, this is indicated.

The presentations are intended only as quick reference diagrams and should be used in conjunction with the cautionary notes on comparisons and limitations due to methodological and definitional differences in data collection procedures, to avoid misleading interpretations.

The rating maps each country's prevalence level onto a scale of 1 to 100, representing the highest and lowest prevalence levels respectively across all reporting countries. The number of countries reporting generally differs from prevalence to prevalence and is stated in the diagram. Date of data collection is also shown.

Prevalence of drug use for the last year reported (LYP) and for lifetime prevalence (LTP) are give per 1000 people (or students in the case of school surveys), except for cannabis and inhalants/volatiles. The prevalence of these drugs is given per 100 people (or students), to accommodate the information on the same scaled diagram. For problem drug use (PDU) the reported figure is generally equivalent to a one-year prevalence rate.

All estimates are subject to sampling and reporting errors, and in the case of the general population surveys confidence intervals are not reported to the EMCDDA at present, but the sample sizes are given in the tables cited as an indication of estimation reliability. For school surveys, refer to the cited tables and the ESPAD source publication.

For the full information on which the displayed data are based, refer to Tables GPS-3, EYE-1, PDU-1 and also to Tables GPS-10, EYE-4, PDU-4 and PDU-5 for a complete list of earlier studies and surveys in all countries.

Notes on school surveys:

The prevalence data presented for schools surveys are for 15/16 year old school students obtained from national surveys. The notes indicate, in some cases, that the surveys are limited to specified regions.

Generally when comparing figures caution is required due to methodological differences and limitations. For methods and definitions used see Methods and definitions - schools surveys.

The data on school pupils are almost exclusively derived from ESPAD surveys (The European school survey project on alcohol and other drugs). The sample sizes and other information are given in statistical bulletin Table EYE-1 and Table EYE-3. For further details see http://www.espad.org.

Notes on general population surveys of all adults:

The results for the last surveys available in each country are presented in the diagram. In the case of the general population surveys confidence intervals are not reported to the EMCDDA at present, but the sample sizes are given in Table GPS-1 as an indication of estimation reliability. In surveys with small sample sizes, results should be interpreted with caution.

Note that cannabis and cocaine use prevalence refers to the drugs in any form. For methods and definitions on population surveys in general, see Methods and definitions - general population surveys of drug use.

Countries report, as far as possible, data for EMCDDA standard age groups (all adults: 15 to 64, young adults: 15 to 34). See Table GPS-3 and Table GPS-10 for details of the precise age groups covered by the surveys. For full information of all surveys available for each country see Table GPS-1 part (i) and Table GPS-1 part (ii); for details of bibliographic references of each survey see Table GPS-0.

Notes on problem drug use estimates:

The range of estimation (either from confidence interval or sensitivity analysis) is not shown in the diagrams; estimates may be made by different methods in different countries. Midpoints of ranges have been calculated in cases where no central estimate was provided to facilitate interpretation and comparisons. The ranges reported may have arisen either from confidence intervals or from a sensitivity analysis. See Table PDU-1 for details.

For further details on data sources, methods and other comments see tables Table PDU-3 and Table PDU-4. See Table PDU-0 for details of bibliographic references.