This visualization shows the correlation between national happiness scores and health expenditures per person, using a line chart to depict the trend across countries. It loads country-level data from a CSV file and renders it with Vega-Lite, using vega-lite-api and d3.csv for data fetching. The chart is customized with config.js for readability, and includes a layer for a least-squares regression line exported from lregression.js, which calculates the linear relationship fit to the data points.