Introduction

Progressively increasing life expectancy and attendant aging of the population is a worldwide phenomenon, particularly in Western economically advanced countries. Forecasts for the coming decades suggest that the trend is likely to intensify, reaching hitherto unimagined proportions. The proportion of the world’s people aged 60 or more in 2011 will double in percentage terms by 2050, when this age group will account for some two billion people and 22 percent of the population (United Nations 2011). These changes in population structure are a consequence of declining fertility and mortality rates (known as the demographic transition) and shifting migration trends. Fertility decline reduces family size and produces smaller cohorts at younger ages, while mortality decline raises life expectancy. The combined outcome is population aging (Alley and Crimmins 2007). Table 1.1 shows the percentage of the population aged 65 and over in selected developed and developing countries in 2014 and 2050.