The elderly population is defined as people aged 65 and over. The share of the dependent population is calculated as total elderly and youth population expressed as a ratio of the total population. The elderly dependency rate is defined as the ratio between the elderly population and the working age (15-64 years) population. The comparability of elderly population data is affected by differences, both within and across countries, in how regions and the geography of rural and urban communities, are defined. Elderly people tend to be concentrated in few areas within each country, which means that a small number of regions will have to face a number of specific social and economic challenges due to population ageing. These demographic trends have a number of implications for government and private spending on pensions, health care, and education and, more generally, for economic growth and welfare. This indicator is measured as a percentage of population.