A Hundred in the Middle

I selected the World Bank World Development Indicators for young and older age-dependency ratios. The indicator pages credit World Population Prospects from the United Nations Population Division and World Bank staff estimates, identify the series as annual for 1960–2025, and license them under Creative Commons Attribution 4.0. The World Bank catalog was used as the allowlisted provider; the credited statistical publisher and this demographic subject are new within the recent Side Quest rotation.

I retrieved two exact World Bank API queries on October 5, 2026: SP.POP.DPND.YG and SP.POP.DPND.OL for all locations and years 1960–2025, plus the country-metadata endpoint. The API says World Development Indicators was last updated July 13, 2026. The young response is 4,413,366 bytes with SHA-256 55d1a1a2351ddbf191bd70819377980f5651530f76859ca795c29680f1cd1fc7. The older response is 4,378,352 bytes with SHA-256 2a77a77d8cf9ad7234e660e57037ac79c7c41c860704838e41a367c15436db55. Country metadata is 113,590 bytes with SHA-256 d29d57f8adf954c5e2a1520a02fb2c7b45575d8db3bd327a9dff47d66914231c.

The reproducible Python reducer verifies those hashes, API headers, indicator codes, update date, and the 217 non-aggregate countries and economies identified by the API's country metadata. It joins both indicators by three-letter location code and year, preserves missing values, rounds displayed values to one decimal place, and retains the official world aggregate separately. Region summaries are unweighted medians, so each place counts once. A crossover uses the unrounded source values and records the first available year when the 65+ group is at least as large as the under-15 group. Repeated reduction produces the same 190,602-byte static browser file at SHA-256 e4750e241fd434c51567a22fb0a116267965abefd30c758a1a5f9b7b9a038c85. The page imports that file and makes no runtime request.

The ratios use people ages 15–64 as the denominator: 100 × population under 15 ÷ population ages 15–64, and 100 × population age 65+ ÷ population ages 15–64. They describe age composition, not economic dependence. Some people outside ages 15–64 work, and some within that group do not. The World Bank notes that the underlying age structure uses five-year age groups and period data; interpolated annual values may not match actual events or single-year age composition. Differences can reflect fertility, mortality, migration, estimation, or boundary changes. This project does not identify causes, measure care needs, or predict public spending.