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 information in the statistical bulletin tables EYE-01, EYE-03, GPS-03, PDU-01.

Prevalence of drug use for the last year reported (LYP) and for lifetime prevalence (LTP) are give per 1000 people (or pupils 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 (1YrP).

The rating relative to all other countries that reported relevant prevalence data is on a single scale of 1 to 100 for all drugs, and shows the prevalence of the country relative to the lowest and highest prevalences reported. The rating maps the country's prevalence level onto its position between the minimum and maximum reported prevalences across all reporting countries. The number of countries reporting generally differs from item to item (and is stated in the diagram); for details of the reporting countries, refer to the cited tables.

Wherever possible, the most recent survey information in the past 5 years (1999–2003) provided to the EMCDDA is shown. In many cases data are not available for the country and in some cases, where alternative estimates of prevalence are available for the same year, this is indicated.

The data reported in the diagrams have been selected as representing the more reliable and comparable of the figures provided to the EMCDDA. 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.

For the full information on which the displayed data are based, refer to Tables GPS-03, EYE-01, PDU-01 and also to Tables GPS-10, EYE-04, PDU-04 and PDU-05 for a complete list of earlier studies and surveys in all countries.

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.

In the case of PDU 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. Reference should be made to the cited tables for details.

Notes on school surveys:

These prevalence data presented for schools surveys are for 15/16 year old school students obtained from national surveys. The survey for Belgium (fl) is the Flemish region only and the German and Turkish ESPAD surveys are limited to the regions specified. In all of the school surveys the method for data collection was classroom based using anonymous, self-completion questionnaires in written test conditions.

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), which are coordinated by The Swedish Council for Information on Alcohol and Other Drugs. (CAN) and Council of Europe (Pompidou Group). ESPAD prevalence figures are reported rounded to the nearest whole percentage point (other sources supply percentages up to one decimal place). The sample sizes and other information are given in statistical bulletin Table EYE-01 and Table EYE-03. For further details see http://www.espad.org.

Notes on general population surveys of all adults:

This table presents the methods and results for the last surveys available in each country. The number indicated in this column is the reference to the corresponding survey in the table presenting all surveys available for each country in the table Table GPS-1. For sources of each survey report see Table GPS-0.

Cocaine use prevalence refers to cocaine in any form.

In surveys with small sample sizes, results should be interpreted with caution.

Countries were asked to report results using, as far as possible, EMCDDA standard age groups (all adults: 15-64, young adults: 15-34). In countries where age ranges are more restrictive prevalence estimates may tend to be slightly higher. Some countries have recalculated their prevalence figures using the EMCDDA standard age groups. For full information see Table GPS-03 and Table GPS-10.

For methods and definitions on population surveys in general, see Methods and definitions - prevalence and patterns of drug use in the general population.

For methods of each survey presented in this table, see Table GPS-1 part (ii) Survey methods.

Notes on problem drug use estimates:

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-01 for details.

For further details on data sources, methods and other comments see tables Table PDU-3. -Prevalence of problem drug use at national level - full database and Table PDU-4-Prevalence of problem drug use at local level - full study listing.

See Table PDU-00 for details of bibliographic references.