An international aid organization is analyzing a chart that displays annual income for ten different population segments (from poorest to richest) for many countries. A junior analyst observes that for Country X, a very low-income nation, all ten segments have extremely low annual incomes, making their representations on the chart appear almost flat and of equal height. Based on this visual evidence, the analyst concludes that income inequality is not a significant problem in Country X and recommends against funding programs aimed at reducing it. As a senior analyst, critique this conclusion and recommendation. What specific calculation should be performed on the raw data to get a more accurate picture of inequality, and why is it superior to the visual impression?