An SVG Radar chart using a circular background

Here we have a Radar chart that has been set to have a circular background grid instead of an angular one. Other than that it's a pretty standard Radar chart.

This goes in the documents header:
<script src="RGraph.svg.common.core.js"></script>
<script src="RGraph.svg.radar.js"></script>
Put this where you want the chart to show up:
<div style="width: 500px; height: 400px" id="chart-container"></div>
This is the code that generates the chart: