Proportion of out-of-marriage births by maternal generation and rank (%).

The count and description of the families of the Basque Country is done using various statistical sources. On the one hand, families are counted through the Population and Housing Census; on the other hand, the operation Demographic Survey (ED), of an intercensal and five-year periodicity, offers information on the formation of families, family size, preferences on the number and spacing of children, as well as numerous other characteristics, using the method of retrospective approximation to demographic phenomena. The count and description of the families of the Basque Country is done using various statistical sources. On the one hand, families are counted through the Population and Housing Census; on the other hand, the operation Demographic Survey (ED), of an intercensal and five-year periodicity, offers information on the formation of families, family size, preferences on the number and spacing of children, as well as numerous other characteristics, using the method of retrospective approximation to demographic phenomena.