一 根据联合国的有关定义,一个国家,65岁以上老年人口占总人口的比率超过7％,即可称为人口老龄化。日本的老年人口比率在1970年时已超过了7％。战后初期,日本的老年人口比率基本在4％～5％之间,随着经济的高速发展,1955年达到5.3％,1965年达6.3％,1970年达到了7.1％。人口老龄化的直接原因是出生率的持续下降和平均寿命的延长,而这两个原因 According to the UN definition, in one country, the population aged over 65 accounts for more than 7% of the total population, which can be called population aging. Japan’s elderly population ratio exceeded 7% in 1970. In the early days after the war, the ratio of the elderly population in Japan was basically between 4% and 5%. With the rapid economic development, it reached 5.3% in 1955, 6.3% in 1965 and 7.1% in 1970. The direct cause of population aging is the continuous decline in birth rates and the extension of average life expectancy, both of which