This interactive bar chart shows monthly values for a selected year, with a slider controlling the year from 2009 to 2014 and a smooth 2-second transition animating the bars to their new heights and colors. The visualization uses D3 v4 with a band scale for months, a linear scale for values, and a quantile color scale to encode magnitude. Data is loaded from six CSV files using d3.queue, and the chart updates by merging entering and existing SVG rect elements via `selection.merge` and applying axis transitions.