In each figure, data labelled “OECD” are simple mean averages of the OECD countries displayed, unless otherwise indicated. Whenever data are available for less than all 38 OECD countries, the number of countries included in the calculation is specified in the figure (e.g. OECD 33).
Each figure specifies the time period covered, and figure notes provide further details when data refer to different time periods for different countries. Countries are referred to by their ISO codes (Table 1).