Fig. 1.

Age composition and dependency ratios in Japan for 1920–2115. a Age composition of the population according to three different groups. b Youth, old-age, and total dependency ratios calculated as the ratio of the number of, respectively, children (up to 14 years), elderly (65 years or over), and both of those dependent populations to the working-age population (15–64 years). The number of those dependents per 100 working adults is indicated. The vertical line shows 2017, when our analysis was conducted. The population data by 2015 is based on population estimates (13); the data thereafter are population projections (14). The age-specific population size was unavailable for 1941–43 because of World War II. For the same reason, Okinawa was excluded for 1945–46