how to fix column width of winrt column chart in windows store app using xaml and c#

how to fix column width of winrt column chart in windows store app using xaml and c#..

my coding is

xaml code:

 <charts:Chart x:Name="chart" Title="My Account Detail"  HorizontalAlignment="Left"  VerticalAlignment="Top" Margin="0,0,0,0" Width="895"  Height="548" Foreground="Black" FontSize="10" >

  </charts:Chart>

and i am adding chart from server side like:

ColumnSeries columnchart = new ColumnSeries();
                        columnchart.DependentValuePath = "Percentage";
                        columnchart.IndependentValuePath = "TestCode";
                                            

                        
                        columnchart.Tag = testPercentageListitem.TestID;
                       // columnchart.SelectionChanged += columnchart_SelectionChanged;
                       
                       columnchart.Tapped+=columnchart_Tapped;
                       
                        chart.Series.Add(columnchart);