The total dependency ratio is the ratio of the sum of the population aged 0-14 plus that aged 65 and over to the population aged 15-64. The child dependency ratio is the ratio of the population aged 0-14 to the population aged 15-64. The old-age dependency ratio is the ratio of the population aged 65 years and over to the population aged 15-64. All ratios are presented as number of dependants per 100 persons of working age (15-64).