This choropleth map colors countries by GDP per capita using a green sequential scale, with twelve nations assigned numeric scores from 0 to 100. It displays a Mercator projection of world geography loaded from world-atlas TopoJSON, rendered as SVG paths via `d3.geoPath`. The code uses `d3.scaleSequential` with `d3.interpolateGreens`, joins GeoJSON features with `topojson.feature`, and appends tooltips plus a legend showing the color range from low to high values.