This bubble chart maps GDP per capita on the x-axis and life expectancy on the y-axis, with circle size encoding population. Using D3 v4’s `d3.csv`, `d3.scaleLinear`, `d3.axisBottom`, and `d3.axisLeft`, it scales population from 200 to 2.11 billion to radii between 1 and 40 pixels. Circles are rendered via SVG with `stroke` and opacity styling, reading data from a gist-hosted CSV. The chart visually explores relationships between economic output, health outcomes, and country population.