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 official life tables prepared by the Department of Statistical Information, Ministry of Health and Welfare. Calculations were made by Shigesato Takahashi, National Institute of Population and Social Security Research, Ministry of Health and Welfare.
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 ageing. But in the more recent period, the declines in mortalilty from a non-infectious or degenerative type of diseases have become much more important in contributing to a lengthening of life expectancy. Hence, the lengthening of life expectacy itself lately joins in contributing to accelerate the population ageing in Japan which is principally caused by fertility decline.
