Replacing axis labels

HTML

<script src="http://www.amcharts.com/lib/3/amcharts.js"></script>
<script src="http://www.amcharts.com/lib/3/serial.js"></script>
<div id="chartdiv" style="width: 100%; height: 130px;"></div>

JavaScript

var chart;

var chartData = [
    {
        "category": "Evaluation",
        "excelent": 20,
        "good": 20,
        "average": 20,
        "poor": 20,
        "bad": 20,
        "limit": 78,
        "full": 100,
        "bullet": 65
    }
];


AmCharts.ready(function () {
    
    // FIRST BULLET CHART
    // bullet chart is a simple serial chart
    chart = new AmCharts.AmSerialChart();
    chart.dataProvider = chartData;
    chart.categoryField = "category";
    chart.rotate = true; // if you want vertical bullet chart, set rotate to false
    chart.columnWidth = 1;
    chart.startDuration = 1;
    
    // AXES
    // category
    var categoryAxis = chart.categoryAxis;
    categoryAxis.gridAlpha = 0;
    
    // value
    var valueAxis = new AmCharts.ValueAxis();
    valueAxis.labelFunction = formatValue;
    valueAxis.maximum = 100;
    valueAxis.axisAlpha = 1;
    valueAxis.gridAlpha = 0;
    valueAxis.stackType = "regular"; // we use stacked graphs to make color fills
    chart.addValueAxis(valueAxis);
    
    // this graph displays the short dash, which usually indicates maximum value reached.
    var graph = new AmCharts.AmGraph();
    graph.valueField = "limit";
    graph.lineColor = "#000000";
    // it's a step line with no risers
    graph.type = "step";
    graph.noStepRisers = true;
    graph.lineAlpha = 1;
    graph.lineThickness = 3;
    graph.columnWidth = 0.5; // change this if you want wider dash
    graph.stackable = false; // this graph shouldn't be stacked
    chart.addGraph(graph);
    
    // The following graphs produce color bands
    graph = new AmCharts.AmGraph();
    graph.valueField = "excelent";
    graph.lineColor = "#19d228";
    graph.showBalloon = false;
    graph.type = "column";
    graph.fillAlphas = 0.8;
    chart.addGraph(graph);
    
    graph = new AmCharts.AmGraph();
    graph.valueField = "good";
    graph.lineColor = "#b4dd1e";
    graph.showBalloon = false;
    graph.type = "column";
    graph.fillAlphas = 0.8;
...