The age structural transition (cont.)
The decline in fertility rates means a reduction in the number of children being born and a change in the proportions of the population in different age groups.
Initially the reduction in the number of children will mean a reduction in the proportion of the population at the youngest age groups and an increase in the proportion of the population at older age groups.
As the large cohorts born before the fertility decline increase in age, the proportions of the population in each age group will change to reflect this, with the relative importance of working ages increasing as these large cohorts reach working age, and later an increase in the relative importance of old age groups.
Proportion of population by broad age group, Japan 1950-2010.
Source: UN Population Division 2011