Melting Data for Multiple Lines
This example visualizes population estimates and projections over time by region, with multiple colored lines tracing each region's trajectory from 1950 to 2100. The chart emphasizes final population values by sorting lines in descending order and using a legend that displays region names with corresponding colors. Built with D3 v5, the code employs `scaleTime`, `scaleLinear`, `scaleOrdinal`, `line`, `curveBasis`, `nest`, and `axisBottom`/`axisLeft` to render the SVG. Data is loaded and melted from two CSV files containing UN population estimates and medium variant projections.