An unfilled SVG Radar chart

A Radar chart that has been set to have no concentric rings on the background grid - just some radial lines that emanate outwards from the center.

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: 600px; height: 500px" id="chart-container"></div>
This is the code that generates the chart:
    data = [
    // Make the tooltips
    tooltips = [];
    seq      = 0;
    data.forEach(function (v,k,arr)
        data[k].forEach(function (v2,k2,arr2)
            tooltips[seq++] = v2 + '%';

    new RGraph.SVG.Radar({
        id: 'chart-container',
        data: data,
        options: {
            backgroundGridColor: 'gray',
            backgroundGridConcentricsCount: 0,
            colors: ['red','black'],
            highlightLinewidth: 2,
            linewidth: 3,
            labels: ['Bob','Reg','Dug','Lou','Joe','Kev','Jon'],
            tooltips: tooltips,
            tickmarksStyle: 'filledrect',
            tickmarksSize: 10