c#中调用EXCEL图表的高深问题：）？

我已经完成调用图表的部分，并且能根据数据画柱状图，但是每根柱子我想在柱子顶部写上代表什么，怎么写程序呢？

Excel.Application myExcel = new Excel.Application ( ) ;

myExcel.Application.Workbooks.Add (true) ;
myExcel.Visible=true;

myExcel.Cells[1,1]=10;
myExcel.Cells[1,2]=20;
myExcel.Cells[1,3]=30;
myExcel.Cells[2,1]=11;
myExcel.Cells[2,2]=13;
myExcel.Cells[2,3]=16;
Excel.Workbook thisWorkbook=myExcel.ActiveWorkbook as Excel.Workbook;
Excel.Worksheet thisWorksheet;

thisWorksheet = thisWorkbook.ActiveSheet as Excel.Worksheet;
Excel.ChartObjects charts =(Excel.ChartObjects)thisWorksheet.ChartObjects(Type.Missing);

Excel.ChartObject chartObj = charts.Add(0, 0, 800, 300);
Excel.Chart chart = chartObj.Chart;
Excel.Range chartRange=thisWorksheet.get_Range("A1","T12");
chart.ChartWizard(chartRange,Type.Missing,Type.Missing,Type.Missing,Type.Missing,Type.Missing,Type.Missing,"月销售比例图","月份","数量",Type.Missing);

Excel.SeriesCollection seriesCollection=
(Excel.SeriesCollection)chart.SeriesCollection(Type.Missing);
Excel.Series series = seriesCollection.Item(seriesCollection.Count);