This chart displays the number of calls per hour over a 24-hour period, using an area chart to emphasize the volume distribution. The data is loaded from a tab-separated file and mapped to a linear scale for both the x-axis (hour) and y-axis (call count). The visualization uses D3 v4 to render SVG elements, including a filled area path and a line path, with gridlines generated via custom axis functions. The chart is titled “PD Calls Per Hour” with axis labels for hour and number of calls, with the area filled in light steelblue and the line stroke in steelblue.