Aging populations and low fertility

Core measure of replacement shortfall — 2.1 is the replacement level for developed countries.

Direct read on how many births are occurring at the population level per 1,000 people.

Rising longevity compounds the aging problem — more years in retirement per person.

Cleanest headline aging metric — share of the population that is elderly.

Best single metric for economic burden — ratio of 65+ population to working-age (15–64).

Shows when low fertility turns into stagnation or outright population decline.

Best measure of whether immigration is offsetting low fertility and aging.

Health system quality indicator that tracks development level — rising rates signal systemic stress.

Absolute population level — the bottom line of births, deaths, and migration.

Whether economies are offsetting aging by extending working lives — key to fiscal sustainability.

Tracks how much the 55+ cohort remains economically active as populations age.

Market signal on healthcare demand — aging populations drive structural growth in medical spending.