CEVAP:

Population in a country or an area can change for many reasons. During peacetime, almost all countries see increases in their population. As the newborn babies grow and reach working age, they enter the market, increasing labor supply.

Immigration is another reason for population change. When people immigrate into a country, some of them enter the labor force and increase the number of workers willing to supply their labor at a given wage rage. Similarly, migrations from a country or an area (due to war, famine, crime etc.) causes a drop in the number of available workers and shifts the labor supply curve left.