GeoChart with date filter, aggregating values over time

HTML

<script src="http://www.google.com/jsapi?fake=.js"></script>
<div id="chart_div"></div>
<div id="control"></div>
<br />
<div id="creativeCommons" style="text-align: center; width: 400px;">
    <a rel="license" href="http://creativecommons.org/licenses/by-nc-sa/3.0/deed.en_US"><img alt="Creative Commons License" style="border-width:0" src="http://i.creativecommons.org/l/by-nc-sa/3.0/88x31.png" /></a><br /><span xmlns:dct="http://purl.org/dc/terms/" href="http://purl.org/dc/dcmitype/InteractiveResource" property="dct:title" rel="dct:type">Code for GeoChart with date filter aggregating values over time</span> by <span xmlns:cc="http://creativecommons.org/ns#" property="cc:attributionName">Andrew Gallant</span> is licensed under a <a rel="license" href="http://creativecommons.org/licenses/by-nc-sa/3.0/deed.en_US">Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License</a>.
</div>

JavaScript

google.load('visualization', '1', {packages: ['controls']});
google.setOnLoadCallback(drawChart);

function drawChart() {
    var data = new google.visualization.DataTable();
    data.addColumn('date', 'Month');
    data.addColumn('string', 'State');
    data.addColumn('number', 'Value');
    data.addRows([
        [new Date(2012, 0, 1), 'AZ', 12],
        [new Date(2012, 0, 1), 'CA', 17],
        [new Date(2012, 0, 1), 'GA', 13],
        [new Date(2012, 0, 1), 'MA', 19],
        [new Date(2012, 0, 1), 'MS', 22],
        [new Date(2012, 0, 1), 'NY', 10],
        [new Date(2012, 0, 1), 'TX', 11],
        [new Date(2012, 0, 1), 'WY', 16],
        [new Date(2012, 1, 1), 'AZ', 23],
        [new Date(2012, 1, 1), 'CA', 13],
        [new Date(2012, 1, 1), 'GA', 19],
        [new Date(2012, 1, 1), 'MA', 15],
        [new Date(2012, 1, 1), 'MS', 29],
        [new Date(2012, 1, 1), 'NY', 14],
        [new Date(2012, 1, 1), 'TX', 12],
        [new Date(2012, 1, 1), 'WY', 18],
        [new Date(2012, 2, 1), 'AZ', 18],
        [new Date(2012, 2, 1), 'CA', 21],
        [new Date(2012, 2, 1), 'GA', 19],
        [new Date(2012, 2, 1), 'MA', 27],
        [new Date(2012, 2, 1), 'MS', 25],
        [new Date(2012, 2, 1), 'NY', 15],
        [new Date(2012, 2, 1), 'TX', 16],
        [new Date(2012, 2, 1), 'WY', 12],
        [new Date(2012, 3, 1), 'AZ', 10],
        [new Date(2012, 3, 1), 'CA', 15],
        [new Date(2012, 3, 1), 'GA', 23],
        [new Date(2012, 3, 1), 'MA', 12],
        [new Date(2012, 3, 1), 'MS', 20],
        [new Date(2012, 3, 1), 'NY', 19],
        [new Date(2012, 3, 1), 'TX', 17],
        [new Date(2012, 3, 1), 'WY', 13],
        [new Date(2012, 4, 1), 'AZ', 12],
        [new Date(2012, 4, 1), 'CA', 18],
        [new Date(2012, 4, 1), 'GA', 16],
        [new Date(2012, 4, 1), 'MA', 13],
        [new Date(2012, 4, 1), 'MS', 27],
        [new Date(2012, 4, 1), 'NY', 14],
        [new Date(2012, 4, 1), 'TX', 19],
        [new Date(2012, 4, 1), 'WY', 11],
       ...