Table 1.
Number of participants in the Youth in Iceland surveys, 1995–2006.
| Year | N | % of population | % males |
| 1995 | 3,814 | 86 | 51 |
| 1997 | 3,912 | 90 | 51 |
| 1998 | 3,723 | 89 | 52 |
| 1999 | 3,549 | 87 | 50 |
| 2000 | 3,220 | 82 | 49 |
| 2001 | 3,069 | 79 | 47 |
| 2002 | 3,226 | 78 | 50 |
| 2003 | 1,699 | 37 | 52 |
| 2004 | 3,805 | 85 | 52 |
| 2005 | 3,713 | 78 | 50 |
| 2006 | 3,670 | 82 | 50 |
Note. In 2003 the Icelandic survey became the local part of the international ESPAD study. This study used a questionnaire too large to implement in full size in class-room setting among 9th and 10th graders. The survey was divided into two parts (A and B), using separate questionnaires. Participants were randomly selected for these two groups. Both questionnaires included measures on substance use but only part A had items referring to illegal use such as hashish and amphetamines. The A part is utilized in this analysis.