The data is based on the assessment of the annual amount of unpaid work for the entire population above the age of 12. These values are taken from the time-budget surveys of the Federal Statistical Office (1991/92, 2001/02, 2012/13). The values of the remaining years are linearly interpolated.
The resulting values for the invested time are multiplied with the state of population above the age of 12 for every year (GENESIS-Database, Code: 12411-005).
The monetary valuation of time spent for household production relies on the assumption that for all activities a unique minimum wage (8,50 € or 7,95 € inflation adjusted for 2010) was paid. There are several theoretically substantiated valuation methods between which one has to choose: The “generalist approach” taken here (in which other wage levels could have been chosen too), the “specialist approach” – where also other wage rates could be chosen –, the “average wage approach” and the “opportunity cost approach”. The applied “generalist approach” with the minimum wage assumption can be seen as a cautious estimation that rather undervalues the “true value” – also because it does not account for absence time.