The NUPRI model is of a Keynesian nature, incorporating both price and wage adjustment mechanisms to solve the system for each year of simulation. It should be noted that both fertility and mortality are endogenously determined within the macroeconomic-demographic-social security model. The fertility level for each year is estimated from a fertility model of the new home economics approach (Butz and Ward, 1979; Ogawa and Mason, 1986). As regards mortality, the expectation of life at birth for each sex is computed as a function of the one-year lagged per capita government medical expenditure measured in real terms.
Based upon a population projection derived from the most recent version of the NUPRI model (Ogawa and Matsukura, 1995), we will examine Japan's future pattern of population aging over the period 1995-2025. Table 1 presents projected results. Japan's total population, which was 125.6 million in 1995, is projected to increase to 128.6 million by 2007. After reaching this peak, the nation's population is expected to decrease continuously to a level of 121.7 million by 2025.
Though not shown in Table 1, the total number of those aged 65 and over more than doubles from 18.6 million in 1990 to 33.4 million in 2021,after which it is projected to decline gradually. Moreover, due to sexualmortality differentials at higher ages, the predominance of women among the aged population is expected to become increasingly pronounced over time. This feminization of the elderly population suggests that in a virtually universal marriage society such as Japan, the number of widows will grow rapidly in the next few decades. Because of declining family support by adult children (Ogawa, 1993; Ogawa and Retherford, 1993b), the increase in elderly widows is very likely to lead to a considerable rise in the demand for institutional care in the years ahead.
Several important points emerge with regard to the age compositional changes displayed in Table 1. First of all, in 1995, the proportion of the population at ages 0-14 is 15.9 percent, and the proportion of those aged 65 and over is 14.8 percent. Throughout the projected period, the former is on the downward trend, but the latter increases continuously. Towards the end of the projected period, however, the growth rate of the share of the elderly population slows down, thus approaching a higher aging plateau (Schurer, Zhao, and Laslett, 1989). In 1998, the elderly aged 65 and over begin to outnumber the young at ages 0-14, as indicated by the index of aging.
Secondly, as indicated in Table 2, although the proportion of those aged 65 and over is presently smaller in Japan than in many other industri
