A household is classified into a given quintile group on the basis of available income (or expenditure) per capita in that household in relation to the distribution of income across the population. For this purpose, all households are weighted, listed according to the increasing value of available income (or expenditure) per capita (from the smallest to the largest). This list is then divided into five equal parts. The first quintile group consists of 20% of persons with the lowest income (or expenditure), while the fifth quintile group – 20% of persons with the highest income (or expenditure).