(2013). The data cover 180 countries, from all World Bank Group country groups: developing East Asia and Pacific (17), developing Europe and Central Asia (19), high-income OECD (31), highincome non-OECD (26), developing Latin America and Caribbean (23), developing Middle East and North Africa (12), South Asia (8), and Sub-Saharan Africa (44). It also has a broad coverage in terms of income levels: high-income OECD (31), high-income non-OECD (26), low-income (29), lower-middle income (46), and upper middle income (48).<sup>16</sup> The world population is growing more slowly and aging at unprecedented speed. While the global population has tripled since the post-war “baby boom” era, population growth is slowing markedly. After increasing for five decades, the proportion of people ages 15 to 64—the typical working-age population—reached a peak of 66 percent of global population in 2012 and is now starting to fall. The rise in the share of dependents is driven mainly by an increase in the share of elderly in highincome and upper-middle income economies. These global trends—slower population growth and population aging—have been shaped by a steady decline in fertility rates and a rapid improvement in life expectancy. In the 1950s, total fertility rates were more than five births per woman, but since then they have steadily declined to 2.45 births per woman in 2015. In parallel, average life expectancy at birth has risen from 47 years in 1950 to 67 years in 2000, while infant mortality has declined.

Demographic change has a profound impact on the share of the global working age population that lives in developing countries, particularly lower-income countries. In 1950, 33 percent of the global working age population lived in high-income countries. Developing East Asia and the Pacific—the region with some of the most rapid fertility declines and life expectancy improvements in recent years—accounted for 28.5 percent of the working-age population, while Sub-Saharan Africa—the region with the most modest improvements—accounted for only 6.7 percent. By 2015, this distribution had shifted substantially: high-income countries accounted for just 19 percent of the global working age population and Sub-Saharan Africa for 11.2 percent. If we take into consideration the global population between 20 and 40 years of age, the share of highincome countries dropped from 32 percent in 1950 to 16.7 percent in 2015.

The working-age population share increased across all groups of countries between 1950 and 2010. Thus, despite the evidence of positive association between an increase in the share of working age population and GDP per capita growth, there are very few cases of countries with a shrinking working age population share over this period. High-income countries have on average a larger share of working age population, peaking at around 67 percent for OECD countries between 2000 and 2010 (Table 2). At the same time the working-age population share in low-income economies is still below the levels observed even in upper middle-income countries before the 1980s. Table 3 shows that not only has the share of working age population been larger in higher income countries, but also the human capital has been higher.

> 16 Tables A1, A2, and A3 in the annex provide additional descriptive statistics.

12