I am creating a dashboard using Visual force page. I have inserted a meter gauge chart on the page. Now I have to set the maximum value dynamically of the chart this should be like 100k,200k,300k....1m or 100m,200m...1B

How can i add this maximum value dynamically like a setting. And add a maximum value.

<apex:outputPanel id="TotalSales">

                            <apex:outputLabel value="Total Sales" styleClass="Headerclass" />

                            <script>
                            MyChart.on('TotalSales', function(config) {
                            config.axes[0].margin=-10;
                            });
                            </script>

                            <div class="metergaugeCSS"  >
                            <apex:chart name="TotalSales" height="200px" width="100%"
                                animate="true" data="{!TotalSales}" >

                                 <apex:legend position="top" font="bold 8px Helvetica" padding="15"/>

                                <apex:axis type="Gauge" position="gauge"
                                    minimum="0"
                                    maximum="{!TotalSales[0].maxValue}" steps="3"  margin="-15">

                                    <div style="text-align: center; margin-top: -45px;">
                                        <apex:outputText value="{0, number,$###,###}">
                                        <apex:param value="{!TotalSales[0].size}"/>
                                        </apex:outputText>

                                       <br/> Total Order Amount <br/> Invoiced


                                    </div>

                                </apex:axis>   

                                <apex:gaugeSeries dataField="size" donut="50"
                                    colorSet="#78c953,#ddd" />
                            </apex:chart>
                            </div>
                           </apex:outputPanel>
================================================= Controller

  //Get values for Total Sales chart representation.
    public List<gaugeData > getTotalSales() {
        List<AggregateResult> totalSales = [select SUM(Order_Amount__c) totalAmount , Show__r.Name showName from Non_Booth_Item__c where  Show__c =:currentShow.Id and Item_Status__c !='cancelled' Group By Show__r.Name ];
        List<gaugeData> data = new List<gaugeData>();
          Integer maxvalue= Integer.valueOf(currentShow.Estimated_Revenue__c);

        if(!totalSales.isEmpty()){

            Decimal i = ((Decimal) totalSales[0] .get('totalAmount') ).setScale(2);
            data.add(new gaugeData(String.valueOf(totalSales[0].get('showName')), i,maxvalue));

        }
        else
        {
            data.add(new gaugeData('', 0,maxvalue));         
        }
        return data ;
    }
=========

//Wrapper class for showing values on gauge for max and minimum value.
    public class gaugeData {
        public String name { get; set; }
        public Decimal size { get; set; }
        public Integer maxValue {get;set;}

        public gaugeData(String name, Decimal data, Integer maxValue) {
            this.name = name;
            this.size = data;
            this.maxValue = maxValue;
        }
    }