This example displays a natural Earth projection world map with semi-transparent teal circles overlaid on each country, sized according to estimated 2018 population data from the UN. The map uses `d3.geoPath` and `d3.geoNaturalEarth1` to render country outlines from TopoJSON, while `d3.scaleSqrt` maps population values to circle radii. A legend with `d3.scaleSqrt` ticks and a color legend for missing data accompany the visualization, which supports zooming via `d3.zoom`.