Highcharts Multiple trend graphs

HTML

<script src="http://code.highcharts.com/highcharts.js"></script>

<div id="result"></div>
<table id="table-sparkline">
    <thead>
        <tr>
            <th></th>
            <th>Today</th>
            <th>Yesterday</th>
            <th>% Change</th>
            <th>YTD Trend</th>
        </tr>
    </thead>
    <tbody id="tbody-sparkline">
        <tr>
            <th>Orders</th>
            <td>833</td>
            <td>750</td>
            <td class="down">-11%</td>
            <td data-sparkline="68, 52, 80, 96 ,68, 52, 80, 96,68, 52, 80, 96 "/>
        </tr>
        <tr>
            <th>Sales</th>
            <td>£33,000,000</td>
            <td>£31,500,000</td>
            <td class="up">13%</td>
            <td data-sparkline="68, 52, 80, 96,88,83,78,75,71,66,55,48,47,46 "/>
        </tr>
        <tr>
            <th>Avg Per Customer</th>
            <td>£18,000</td>
            <td>£21,123</td>
            <td class="down">-9%</td>
            <td data-sparkline="1,100,50,33,110,90,-10,90 "/>
        </tr>
    </tbody>
</table>

CSS

#result {
	text-align: right;
	color: gray;
	min-height: 2em;
}
#table-sparkline {
	margin: 0 auto;
    border-collapse: collapse;
}
th {
    font-weight: bold;
    text-align: left;
}
td.down {color:red;}
td.up {color:green;}

td, th {
    padding: 5px;
    border-bottom: 1px solid silver;
    border-right: 1px solid silver;
    height: 20px;
}

thead th {
    border-bottom: 1px solid gray;
}

.highcharts-tooltip>span {
	background: white;
	border: 1px solid silver;
	border-radius: 3px;
	box-shadow: 1px 1px 2px #888;
	padding: 8px;
}

JavaScript

$(function () {
    /**
     * Create a constructor for sparklines that takes some sensible defaults and merges in the individual
     * chart options. This function is also available from the jQuery plugin as $(element).highcharts('SparkLine').
     */
    Highcharts.SparkLine = function (options, callback) {
        var defaultOptions = {
            chart: {
                renderTo: (options.chart && options.chart.renderTo) || this,
                backgroundColor: null,
                borderWidth: 0,
                type: 'area',
                margin: [2, 0, 2, 0],
                width: 120,
                height: 20,
                style: {
                    overflow: 'visible'
                },
                skipClone: true
            },
            title: {
                text: ''
            },
            credits: {
                enabled: false
            },
            xAxis: {
                labels: {
                    enabled: false
                },
                title: {
                    text: null
                },
                startOnTick: false,
                endOnTick: false,
                tickPositions: []
            },
            yAxis: {
                endOnTick: false,
                startOnTick: false,
                labels: {
                    enabled: false
                },
                title: {
                    text: null
                },
                tickPositions: [0]
            },
            legend: {
                enabled: false
            },
            tooltip: {
                backgroundColor: null,
                borderWidth: 0,
                shadow: false,
                useHTML: true,
                hideDelay: 0,
                shared: true,
                padding: 0,
                positioner: function (w, h, point) {
                    return { x: point.plotX - w / 2, y: point.plotY - h};
                }
            },
            plotOptions: {
          ...