Figure 1.

Flowchart showing numbers of participating children from W1 to W3.

Notes: Children characterized as “new” participants for W2 and W3 were children who reached the age of 9 years in the interim and thus became eligible for filling in the questionnaire for the first time in that wave.

Abbreviations: W1, wave 1 (2003); W2, wave 2 (2004); W3, wave 3 (2005).