This survey has been conducted every year since 1993 via an internet-based questionnaire. Over the course of the survey's history the contributing and funding agencies have changed, resulting in various titles of the survey. Despite these changes the questionnaire has remained largely the same with slight revisions from year to year. The 2001 questionnaire included modules on household demographics, employment and pensions, housing, health, income, financial assets, and opinions on economic and psychological topics. Approximately 2,138 households participated during this ninth wave of the survey.