5. Future Trends of Population Aging in Sub-national Areas of Japan
According to the projections of future populations by prefectures made in 1997 by National Institute of Population and Social Security Research (Table 9), the percentage of total population in the elderly ages of 65 and over will exceed 20.0% for all of 47 prefectures except for Okinawa in 2015 when it will present 25.2% for the nation, under the assumption that the age-specific rates of fertility, mortality and net-migration for the period of 1990 to 1995 will not be unchanged for the future. Also, among 47 prefectures, Yamaguchi, where it was 22.3% in 1995, will indicate the highest (30.7%), while Okinawa, where it was 13.9% in 1995, will record the lowest (19.1%). In addition to Yamaguchi, the remote rural prefectures of Kochi, Akita and Shimane will record higher than 30.0%, on the other hand the metropolitan or urban prefectures of Shiga, Saitama, Miyagi, Ibaraki, Tochigi, Kanagawa, Yamanashi, Aichi, Fukuoka and Nara, in addition to Okinawa, the most remote prefecture, will indicate lower than 25.0% in 2015.
In 2020, all of 47 prefectures will exceed 20.0% as Okinawa will present 21.7% in the proportion. In 2025, when the nation will show 27.4% in the elderly proportion, 14 prefectures, among those which Akita will record the highest (33.8%), will present 30.0% or larger. Under the assumption described above, the discrepancy in the degree of population aging, in terms of the proportion of the population at the ages of 65 and over, between 47 prefectures, will continue to decrease, because the coefficients of variation for the proportion will decrease in future every five year after 1995 (Table 9).
