1. Total Dependency Ratio ((Age 0–14 + Age 65+)/Age 15–64)https://population.un.org/wpp/Download/Standard/Population/
2. Percentage of Total Population by Broad Age Group, Both Sexes (per 100 Total Population)https://population.un.org/wpp/DataQuery/
3. Is Retirement Age Delay Effective for Alleviating the Pressure from Population Ageing?;Yuan;Popul. Res.,2006
4. World Population Prospects 2019,2019