Which of the following statement (s) is /are not correct about ageing population?

Ageing population is a new phenomenon of the twenty first century.

Population ageing is the process by which the share of the older population becomes proportionally larger. This is a new phenomenon of the twentieth century. In most of the developed countries of the world, population in higher age groups has increased due to increased life expectancy. With a reduction in birth rates, the proportion of children in the population has declined.