This world choropleth colors countries by a cost index, where values above 100 indicate higher-than-baseline costs and values below 100 indicate lower costs. The map uses an SVG projection with D3 v7’s `geoNaturalEarth1` projection, `d3.geoPath`, and a sequential `d3.interpolatePlasma` color scale. Country geometries come from a remote GeoJSON file, and hovering displays a tooltip with each country’s specific index value. Countries without data appear in a muted gray, while a fixed legend explains the color scale.