a current aggregate median age of 27 years, but aging is also proceeding rapidly and the median is projected to reach 37 years in 2050.

Figure 3-16 plots past estimates and projections of the proportion aged 65+ for each of the world regions. Large regional differences are apparent. In 2010, proportions 65+ in Europe (16.2) and North America (13.2) are substantially higher than in Latin America (6.9), Asia (6.7) and Africa (3.5). By 2050 these proportions are expected to have risen further, reaching 26.9 percent in Europe and 21.6 percent in North America. The steepest increases are projected for Asia and Latin America, where levels will more than double and reach above today’s European levels. Africa will also age, but slowly, and will remain the youngest region.

Figure 3-17 compares the United States with other high-income countries. By mid-century the proportion aged 65+ is projected to reach 21 percent in the United States and substantially higher in other rich countries (over 30 percent in Germany, Italy, and Spain and 36 percent in Japan). The reason for this difference is the relatively high fertility in the United States and the low fertility in Germany, Italy, Japan, and Spain. In addition, the United States is expected to have higher mortality and migration rates. Other high-income countries therefore face more pronounced aging than does the United States.

UNCERTAINTY IN POPULATION PROJECTIONS

It is obvious that many assumptions are required for a population projection. Painful actions such as raising the retirement age might be taken

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FIGURE 3-16  Share of the population aged 65+ in five world regions, 1950–2050. SOURCE: United Nations (2011).



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