According to the Figure 1 presenting the prefectures with higher percentage of the total population in the ages of 65 and over than the national average in time-series, similar patterns may be observed from 1970 to 1990. Therefore, it can be said that discrepancy in the percentage of the total population in the elderly ages between 47 prefectures had been kept for the period of 1970 to 1990. However, in 1995, it was altered due to expansion of the areas, where the percentage of total population in the elderly exceeded the national average, to Aomori and Hokkaido, etc. Figure 2, depicting time serial change in the coefficients of variation for the percentage of the total population in the elderly ages, explains that such discrepancy was largest in 1970 and thereafter it had decreased. Therefore, it is known that population aging has expanded spatially in recent years.
Differences in the degree of population aging between 47 prefectures, are observed in other indices. Aged dependency ratio, or the ratio of the population at the ages of 65 and over against 100 persons at the ages of 15 to 64 as of 1995 recorded the highest for Shimane (35.0) among 47 prefectures. Following after Shimane, the remote rural prefectures of Kochi, Kagoshima Akita, Yamagata, and Tottori showed higher than 30. On the other hand, the metropolitan prefectures of Saitama, Kanagawa, Chiba, Tokyo, Aichi, Osaka and Nara, and Okinawa, the most remote island prefecture, indicated lower than 20.0. Also, other metropolitan prefectures such as Ibaraki, Tochigi, Gumma, Gifu, Mie, Shiga, Kyoto, and Hyogo showed lower than 25, although the national average was 21.0. Therefore, much clearer pattern of discrepancy in the degree of population aging between metropolitan or urban prefectures and rural prefectures was observed in the aged dependency ratio than in the percentage of total population in the elderly ages as of 1995 (Table 1).
