Как разделить три отдельных столбца на один большой столбец?

Question

У меня есть такой тип данных в моей Datatable.Представьте себе, что ("2019_WK1", "2019_WK2", "2019_WK3") - это имена трех столбцов, и поэтому мне нужно разделить 2019 (год) в одной большой объединенной ячейке (верхний "WK1", "WK2", "WK3")) ячейки столбца в C #.

с использованием Excel = Microsoft.Office.Interop.Excel;

Ниже приведен мой код данных:

Excel.Application xlApp;
            Excel.Workbook xlWorkBook;
            Excel.Worksheet xlWorkSheet;
            object misValue = System.Reflection.Missing.Value;
            Excel.Range chartRange;

            xlApp = new Excel.Application();
            xlWorkBook = xlApp.Workbooks.Add(misValue);
            xlWorkSheet = (Excel.Worksheet)xlWorkBook.Worksheets.get_Item(1);

            //add data 
            xlWorkSheet.Cells[1, 1] = "Retailer";
            xlWorkSheet.Cells[1, 2] = "Brand";
            xlWorkSheet.Cells[1, 3] = "2019_WK1";
            xlWorkSheet.Cells[1, 4] = "2019_WK2";
            xlWorkSheet.Cells[1, 5] = "2019_WK3";


            xlWorkSheet.Cells[2, 1] = "Lulu";
            xlWorkSheet.Cells[2, 2] = "Perisil";
            xlWorkSheet.Cells[2, 3] = "25";
            xlWorkSheet.Cells[2, 4] = "26";
            xlWorkSheet.Cells[2, 5] = "23";

        xlWorkSheet.Cells[3, 1] = "Lulu";
            xlWorkSheet.Cells[3, 2] = "Ariel";
            xlWorkSheet.Cells[3, 3] = "26";
            xlWorkSheet.Cells[3, 4] = "28";
        xlWorkSheet.Cells[3, 5] = "29";

        xlWorkSheet.Cells[4, 1] = "Danube";
            xlWorkSheet.Cells[4, 2] = "Omo";
            xlWorkSheet.Cells[4, 3] = "27";
            xlWorkSheet.Cells[4, 4] = "28";
        xlWorkSheet.Cells[4, 5] = "30";

        xlWorkSheet.Cells[5, 1] = "Danube";
            xlWorkSheet.Cells[5, 2] = "Tide";
            xlWorkSheet.Cells[5, 3] = "24";
            xlWorkSheet.Cells[5, 4] = "23";
        xlWorkSheet.Cells[5, 5] = "29";

        xlWorkSheet.Cells[6, 1] = "Bin Dawood";
            xlWorkSheet.Cells[6, 2] = "Perisil";
            xlWorkSheet.Cells[6, 3] = "26";
            xlWorkSheet.Cells[6, 4] = "27";
        xlWorkSheet.Cells[6, 5] = "28";

xlWorkBook.SaveAs("d:\\csharp.net-informations.xls", Excel.XlFileFormat.xlWorkbookNormal, misValue, misValue, misValue, misValue, Excel.XlSaveAsAccessMode.xlExclusive, misValue, misValue, misValue, misValue, misValue);
            xlWorkBook.Close(true, misValue, misValue);
            xlApp.Quit();

            releaseObject(xlApp);
            releaseObject(xlWorkBook);
            releaseObject(xlWorkSheet);

            MessageBox.Show("File created !");
        }

Мне нужно, как этот типстолбцы

  ____________________________
  |            2019           |
  |___________________________|
  |  WK1   l   WK2  l   WK3   |
  |________l________l_________|
  |  25    |   26   |   23    |
  |  27    |   29   |   24    |
  ___24________25_______22_____