A simple measure of the number of dependants that each 100 people in the productive years must support is

The simple measure of the number of dependents that each 100 people in the productive years must support is called the "dependency ratio." The dependency ratio is a ratio that compares the number of dependent individuals, such as children or elderly people, to the number of working-age individuals in a population. The working-age population is typically defined as individuals between the ages of 15 and 64 years old. For example, if there are 50 dependent individuals for every 100 working-age individuals, the dependency ratio would be 50:100, or 50%. This means that each 100 people in the productive years must support 50 dependents. The dependency ratio is an important measure for understanding the financial and economic burden that dependent individuals can place on the working-age population. It is often used by policymakers to help plan for social security, healthcare, and other services that are necessary for the well-being of a population.