How to display the percentage value on piechart?

Question

I have developed an apex pie chart. I want to display "percentage value" on the pie chart like below

But am getting the chart Like this:

How to do this ?

My apex class:
public class PieChartController {

public Decimal result{get;set;}
public Decimal result1{get;set;}
public Decimal totalRecords {get;set;}
public decimal yesVal{get;set;}
public Decimal noVal{get;set;}


    public List<PieWedgeData> getPieData() {
         List<PieWedgeData> data = new List<PieWedgeData>();
         totalRecords = [select count() from Case];

         result = [select count() from case where Spam__c != TRUE AND Type ='Complaint' AND StopSurvey__c = 'Yes'  AND RecordType.ID != '012b0000000cVxi' AND ClosedDate <= THIS_MONTH AND ClosedDate >= LAST_N_MONTHS:12 AND (SubType__c !='GARANTIA-ORIGINAL' OR SubType__c !='GARANTIA-TRANSFERIDO' OR SubType__c !='Warranty')];

         result1 = [select count() from case where Spam__c != TRUE AND Type ='Complaint' AND StopSurvey__c = 'No' AND RecordType.ID != '012b0000000cVxi' AND ClosedDate <= THIS_MONTH AND ClosedDate >= LAST_N_MONTHS:12 AND (SubType__c !='GARANTIA-ORIGINAL' OR SubType__c !='GARANTIA-TRANSFERIDO' OR SubType__c !='Warranty')];

         yesVal=(result/totalrecords)*100;
         noVal=(result1/totalRecords) * 100;
         data.add(new PieWedgeData('% of StopSurvey Yes', yesVal));
         data.add(new PieWedgeData('% of StopSurvey No', noVal));

        return data;
    }

    // Wrapper class
    public class PieWedgeData {

        public String name { get; set; }
        public decimal data { get; set; }

        public PieWedgeData(String name, decimal data) {
            this.name = name;
            this.data = data;
        }
    }
}

My VF page:

<apex:page controller="PieChartController" title="Pie Chart">
    <apex:chart height="350" width="450" data="{!pieData}">
        <apex:pieSeries dataField="data" labelField="name">


         </apex:pieSeries>
         <apex:legend position="right">
         </apex:legend>
    </apex:chart>
    </apex:page>