1. Working age and pensionable age populations based on State Pension Age (SPA) for a given year. Between 2012 and 2018, SPA will change from 65 years for men and 61 years for women, to 65 years for both sexes. Then between 2019 and 2020, SPA will change from 65 years to 66 years for both men and women. Between 2034 and 2046, SPA will increase in two stages from 66 years to 68 years for both sexes. This is based on SPA under the 2011 Pensions Act.
2. Dependency ratios can be defined in different ways, but here are defined as the number of children aged under 16 and the number of people of state pension age per 100 people of working age. These ratios should be interpreted with care. For example, a simple interpretation is the number of older people or children who are 'dependent' on the working age population, the assumption being that most older people and children are not economically active. The reality is of course much more complex, since - to give just a few reasons - many people of typically working age are unemployed or economically inactive (e.g. at school or university), the age at which people retire varies greatly and many retired people are financially independent. However, these 'dependency' ratios provide a useful way to examine the relative age structure of the population.
3. UK Statistics Authority (2011). Assessment Report 113: Statistics on Population and Demography in Scotland PDF document which can be found on the UK Statistics Authority website.
4. More information on the Eurostat projections can be found on the Eurostat website.