Income is an important basis for measuring development in different countries. But total income is not a useful parameter because the population of different countries is different. So by comparing total income, we do not get to know how much income each person is earning, which may be known as average income or per capita income. For this reason, we compare the average incomes, which is obtained by dividing the total income by the total population of the countries. That's why average income is an important parameter to understand development.