A pie chart breaks down car registrations in Austin, Texas by fiscal year from 2012 to 2021, with each slice sized by the number of cars and a legend listing each year. The chart uses D3 v5’s `pie`, `arc`, and `scaleOrdinal` APIs, along with SVG paths, to render the segments and legend. Animated hover effects use `transition` to show a tooltip with the year’s registration count, driven by mouseover and mouseout events. Data is loaded asynchronously from a GitHub gist CSV via `d3.csv`.