Bubble percents

HTML

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

CSS

body {
    font-family: Verdana;
    font-size: 12px;
    padding: 10px;
}
#chartdiv {
	width	: 100%;
	height	: 130px;
}

JavaScript

var chart = AmCharts.makeChart("chartdiv", {
    "type": "xy",
    "pathToImages": "http://www.amcharts.com/lib/3/images/",
    "theme": "none",
    "dataProvider": [{
        "y": 0,
        "x1": 5,
        "x2": 10,
        "x3": 15,
        "x4": 55,
        "x5": 65,
        "x6": 80,
        "x7": 85
    }],
    "valueAxes": [{
        "minimum": 0,
        "maximum": 100,
        "unit": "%",
        "unitPosition": "right",
        "position":"bottom",
        "axisAlpha": 0,
        "autoGridCount": false,
        "gridCount": 5,
        "minorGridEnabled": true,
        "minorGridAlpha": 0.03
    }, {
        "minimum": -10,
        "maximum": 10,
        "axisAlpha": 0,
        "labelsEnabled": false,
        "axisAlpha": 0,
        "position": "left"
    }],
    "startDuration": 1.5,
    "sequencedAnimation": false,
    "graphs": [{
        "balloonText": "[[x]]%",
        "bullet": "circle",
        "bulletBorderAlpha": 0.8,
		"bulletAlpha": 0.6,
        "lineAlpha": 0,
        "fillAlphas": 0,
        "xField": "x1",
        "yField": "y",
        "minBulletSize": 50,
        "maxBulletSize": 50
    }, {
        "balloonText": "[[x]]%",
        "bullet": "circle",
        "bulletBorderAlpha": 0.8,
		"bulletAlpha": 0.6,
        "lineAlpha": 0,
        "fillAlphas": 0,
        "xField": "x2",
        "yField": "y",
        "minBulletSize": 50,
        "maxBulletSize": 50
    }, {
        "balloonText": "[[x]]%",
        "bullet": "circle",
        "bulletBorderAlpha": 0.8,
		"bulletAlpha": 0.6,
        "lineAlpha": 0,
        "fillAlphas": 0,
        "xField": "x3",
        "yField": "y",
        "minBulletSize": 50,
        "maxBulletSize": 50
    }, {
        "balloonText": "[[x]]%",
        "bullet": "circle",
        "bulletBorderAlpha": 0.8,
		"bulletAlpha": 0.6,
        "lineAlpha": 0,
        "fillAlphas": 0,
        "xField": "x4",
        "yField": "y",
        "minBulletSize": 50,
        "maxBulletSize": 50
    }, {
        "balloonText":...