This interactive stacked bar chart displays age distributions across provinces, rendered with SVG and animation via D3.js (version 3.5.6). Users can toggle between raw counts and percentage of total using radio buttons, which triggers transitions recalculating the stack layout with `d3.layout.stack()` and updating the y-axis tick format. The chart reads from data3.csv and uses `d3.scale.ordinal()` for the x-axis, category20 colors for age bands, and a custom tooltip on hover.