ElementStacks

HTML

<script src="http://highcharts.com/js/testing.js"></script>
<div id="container" style="height: 400px"></div>

JavaScript

var chart = new Highcharts.Chart({
    chart: {
        renderTo: 'container',
        defaultSeriesType: 'line'
    },
    tooltip: {
        formatter: function(){
            return Highcharts.dateFormat("<i>%Q/%Y", this.x)
                  + '  ' + Highcharts.dateFormat("%H:%M", this.x)
                  + '</i><br />' + this.series.name + ': <b>' + this.y
                  + '</b>';
        }
    },
    xAxis: {
        type: 'datetime'
    },
    series: [{
        data: [29.9, 71.5, 106.4, 129.2, 144.0, 176.0, 135.6, 148.5, 216.4, 194.1, 95.6, 54.4],
        pointStart: Date.UTC(2011,0,1),
        pointInterval: 24 * 3600 * 1000
    }]
});