1. The trends represent the available information on national potency / purity for each drug in the EU Member States and Norway, weighted by country population sizes to form an overall EU trend. All series indexed to a base of 100 in 2004.
2. Countries missing drug price information for two or more consecutive years are not included in the trend calculations: the trend for amphetamine on nineteen countries (80 % of the EU population 15-64), cocaine on twenty-two countries (90 % of the EU population 15-64), ecstasy on fourteen countries (58 % of the EU population 15-64), herbal cannabis on fourteen countries (65 % of the EU population 15-64), and cannabis resin on fifteen countries (66 % of the EU population 15-64). Trends for other drugs are not available due to insufficient data.
3. Additionally, where 2009 data are missing (fifteen cases) 2008 prices are used; for missing 2004 data (fifty-five cases) 2005 prices are used; data missing for other years (twenty-three cases) have been interpolated from adjacent years.
population 15-64 data: http://epp.eurostat.ec.europa.eu/
See also 'General notes for interpreting data' on the Explanatory notes and help page.
Potency / purity data: Reitox National Focal Points
(see the help page for information about formats etc.)