fresh block
A stacked area chart displays how four unnamed data categories change over time, with each layer labeled at the right edge and a y-axis formatted as a percentage. The code loads tab-separated data via `d3.tsv`, parses dates with `d3.timeParse`, and builds the visualization using `d3.stack`, `d3.area`, `d3.scaleTime`, `d3.scaleLinear`, and `d3.scaleOrdinal` with `d3.schemeCategory10`. SVG rendering and axes are created with `d3.axisBottom` and `d3.axisLeft`.