This bar chart displays BMW sales volumes by region for 2022, using the `Sales_Volume` field from `data.csv`, aggregated via `d3.rollups`. Each bar is colored by its corresponding country, and hovering over a bar highlights it in black while dimming others, showing a tooltip with the exact sales figure. The visualization uses D3.js v7's SVG rendering, with scales created via `d3.scaleLinear` and `d3.scaleBand`, and interactive hover events implemented through D3's `.on('mouseover')` and `.on('mouseout')` handlers.