Table 6. Contribution of Mortality Reduction in Each of Major Age Groups to the Increase in Life Expectancy, Japan: 1955-1990
Note: Data used in this series of calculation are based on the otticial lite tables preparea by tne Department of Statistical Information, Ministry of Health and Welfare. Calculations were made by Shigesato Takahashi, Institute of Population Problems, Ministry of Health and Welfare.
ing to these tables, for example between 1955 and 1960, much contribution has been noted among the young ages under 15 years toward anincrease in the life expectancy. There about 65 percent are attributable to mortality reductions in this young age group. On the other hand, however,in recent years, say 1985-1990, the contribution in the improvement in infancy and childhood has become considerably outshined by the contributions in adult and old-age mortality. When the effect of mortality declines among the elderly becomes more pronounced than among the youth population, then, it would be inevitable that the population ageing becomes an important political issue which demographers could not clearly envisage.
Table 7 denotes a similar decompositional table in which the amount of contribution to an increase in life expectancy can be estimated by each cause of death group for Japan. From Table 7, it is evident that in the early period of the postwar era, say in 1955-70, the declines in mortality from infectious and parasitic diseases were most important causes of death, thus having played a role at least temporarily toward reducing population age-
