Coloring each column individually according to category budget

HTML

<script type="text/javascript" src="http://www.amcharts.com/lib/3/amcharts.js"></script>
<script type="text/javascript" src="http://www.amcharts.com/lib/3/serial.js"></script>
<script type="text/javascript" src="http://www.amcharts.com/lib/3/themes/none.js"></script>
<div id="chartdiv"></div>

CSS

#chartdiv {
	width		: 100%;
	height		: 300px;
	font-size	: 11px;
}

JavaScript

// source data
var chartData = [{
    "category": "January",
    "limit": 153,
    "bullet": 153,
    "percent": "-17.0",
    "full": 153
}, {
    "category": "February",
    "limit": 135,
    "bullet": 162,
    "percent": "-12.7",
    "full": 135
}, {
    "category": "March",
    "limit": 123,
    "bullet": 94,
    "percent": "-3.7",
    "full": 123
}, {
    "category": "April",
    "limit": 86,
    "bullet": 70,
    "percent": "-6.4",
    "full": 86
}, {
    "category": "May",
    "limit": 85,
    "bullet": 92,
    "percent": "-15.3",
    "full": 85
}, {
    "category": "June",
    "limit": 67,
    "bullet": 38,
    "percent": "-7.5",
    "full": 67
}, {
    "category": "July",
    "limit": 67,
    "bullet": 0,
    "percent": "-4.4",
    "full": 67
}, {
    "category": "August",
    "limit": 60,
    "bullet": 0,
    "percent": "-4.4",
    "full": 60
}, {
    "category": "September",
    "limit": 76,
    "bullet": 0,
    "percent": "-4.4",
    "full": 76
}, {
    "category": "October",
    "limit": 109,
    "bullet": 0,
    "percent": "-4.4",
    "full": 109
}, {
    "category": "November",
    "limit": 113,
    "bullet": 0,
    "percent": "-4.4",
    "full": 113
}, {
    "category": "December",
    "limit": 127,
    "bullet": 0,
    "percent": "-4.4",
    "full": 127
}];

// pre-process data
for (var x in chartData) {
    // color bar in red if it's under budge
    if (chartData[x].bullet < chartData[x].limit)
        chartData[x].color = "#a70d1c";
    else
        chartData[x].color = "#0c0";
    
    // set alpha to semi-transparent for upcoming months we don't
    // have data for yet
    if (0 == chartData[x].bullet) {
        chartData[x].alpha = 0.3;
        chartData[x].color = "#ccc";
    }
}

var chart = AmCharts.makeChart("chartdiv", {
    "type": "serial",
    "theme": "none",
    "percentPrecision": 1,
    "precision": 1,
    "dataProvider": chartData,
    "startDuration": 1,
    "graphs": [{
        "valueField": "limit",
        "lineColor":...