Highcharts Bubble chart

Bubble chart

HTML

<script src="https://code.highcharts.com/highcharts.js"></script>
<script src="https://code.highcharts.com/highcharts-more.js"></script>
<script src="https://code.highcharts.com/modules/exporting.js"></script>

<div id="container" style="height: 600px; min-width: 510px; max-width: 900px; margin: 0 auto"></div>

CSS

.highcharts-tooltip h3 {
    margin: 0.3em 0;
}

JavaScript

$(function () {

var json = 
[
{ "x": 25, "y": 50, "z": 5000, "key": "A", "name": "Issue1",color: '#ED4466' },
{ "x": 26, "y": 55, "z": 4600, "key": "B", "name": "Issue2" ,color: '#7ED300'},
{ "x": 30, "y": 56, "z": 3000, "key": "C", "name": "Issue3" ,color: '#3EDDD8'},
{ "x": 32, "y": 60, "z": 345, "key": "D", "name": "Issue4" ,color: '#8458C7'},
{ "x": 35, "y": 62, "z": 2500, "key": "E", "name": "Issue5" ,color: '#41C095'},
{ "x": 39, "y": 64, "z": 2335, "key": "F", "name": "Issue6" ,color: '#FFD000'},
{ "x": 41, "y": 56, "z": 450, "key": "G", "name": "Issue7" ,color: '#B270FF'},
{ "x": 45, "y": 70, "z": 150, "key": "H", "name": "Issue8" ,color: '#B23C9B'},
{ "x": 47, "y": 72, "z": 3700, "key": "I", "name": "Issue9" ,color: '#0096BC'},
{ "x": 48, "y": 72, "z": 56, "key": "I", "name": "Issue90" ,color: '#E5C214'},
{ "x": 49, "y": 72, "z": 66, "key": "I", "name": "Issue91" ,color: '#4BA7BC'},
{ "x": 55, "y": 72, "z": 89, "key": "I", "name": "Issue92" ,color: '#C0CC3D'},
{ "x": 57, "y": 72, "z": 600, "key": "I", "name": "Issue93" ,color: '#BC6E5B'},
{ "x": 60, "y": 72, "z": 20, "key": "I", "name": "Issue94" ,color: '#6D9249'}

];
                  
    $('#container').highcharts({

        chart: {
            type: 'bubble',
            plotBorderWidth: 1,
            zoomType: 'xy'
        },

        legend: {
            enabled: false
        },

        title: {
            text: 'test'
        },

        

        xAxis: {
            gridLineWidth: 1,
            title: {
                text: 'First Response Time'
            },
            labels: {
                format: '{value} hr'
            }
        },

        yAxis: {
            startOnTick: false,
            endOnTick: false,
            title: {
                text: 'Response Time'
            },
            labels: {
                format: '{value} hr'
            },
            maxPadding: 0.0,

        },

        tooltip: {
            useHTML: true,
            headerFormat:...