A streamgraph visualizes the total number of persons of concern grouped by country of origin, summing categories like refugees, asylum-seekers, and internally displaced persons. The interactive D3.js v4 visualization uses `d3.stack` with a wiggle offset and inside-out ordering, rendering static SVG paths with d3-area, a time-based x-scale, and labels positioned via d3-area-label. Data is fetched from a remote JSON file, filtered to countries with over one million people, and interpolated across years using d3's bisector and date range methods.