A ratio that measures the number of dependents in the population relative to the number of economically active. A higher ratio indicates greater reliance of the non-working population on goods and services produced by the working population in the society. Let N_o be the size of the population aged over 65, N_y the population aged below 15, and N_a the economically active population aged 15–64. The old-age-dependency ratio is N_o/N_a, the young-age-dependency ratio is N_y/N_a, and the total dependency ratio is (N_y + N_o)/N_a. The old-age-dependency ratio is increasing in many countries and is an important factor in the pensions crisis.