A9 World Choropleth Map visualizes GDP per capita across countries in 2022 using a Mercator projection and a threshold color scale from `d3.scaleThreshold` and `d3.schemeBlues`. The map, rendered as SVG, colors each country path via `d3.geoPath`, with gray for missing data, and includes interactive tooltips showing country name and GDP value on mouseover. A separate SVG legend, built with `d3.legendColor`, displays the color thresholds. The code loads GeoJSON country boundaries and CSV economic data using `d3.json` and `d3.csv` with a queued `d3.queue`.