A stationary type of population is a state of society when demographic processes do not tend to change, as well as in other situations in which the age composition remains unchanged for a long period of time. This concept was developed at the beginning of the 20th century thanks to research in the field of labor economics. Researchers conducted a comparative analysis of fertility and mortality in European countries; indicators of natural and migration growth and population density were determined. As a result, the study revealed some statistics regarding long-term demographic indicators: people after reaching the age of legal capacity