都道府県別 売上の推移
A choropleth map of Japan displays the annual sales figures for each prefecture from 2009 to 2017, with a dropdown menu to select the year. Animated transitions smoothly recolor each prefecture's fill, while proportional circles, centered on each prefecture's capital, scale their radius to represent the sales value. The visualization uses D3.js v3 with a Mercator projection via `d3.geo.path()`, a linear scale for color and radius, and queues external JSON and TSV files to load geographic and sales data.