This interactive bar chart compares violent crime rates per 100,000 population across 15 U.S. states and the District of Columbia for 2002 and 2014. Clicking the gray year label toggles between the two datasets, animating bar heights and colors via D3 v7 transitions. The chart uses `d3.scaleBand` and `d3.scaleLinear` for axes, with SVG rectangles rendered through `d3.selectAll` and a custom `update` function. Axis labels and margins are configured manually; data appears hardcoded in arrays rather than loaded from an external file.