Earnings inequality can be assessed using a variety of statistics. The indicator used here is the "decile ratios", which is obtained by comparing earnings in the top and the bottom deciles of the distribution (the 10% of workers with the highest and
lowest earnings) to median earnings (the earnings level which divides employees into two groups of equal size). In this section, D9 denotes the upper limit of the 9th decile of the earnings distribution (which is equal to the lower limit of the top decile),
D1 is the upper limit of the bottom decile while D5 denotes median earnings.