<%@ Import Namespace="System.Data" %>
<%@ Import Namespace="System.Data.OleDb" %>

<script language="C#" runat="server">
    void SubmitBtn_Click(Object sender, EventArgs e)
    {
        // Set the connection info to the database
        string strDBPath = Server.MapPath(".") + "\\" + "population2.mdb";
        string strAccessConn = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + strDBPath;

        // Set select query string to return 4 columns of data
        string sTable = "states";
        string strAccessSelect = "SELECT year, [" + listBox1.SelectedItem.Text + "],
						Increase, [% Increase] FROM " + sTable;

        // Open connection to the database
        OleDbConnection myConnection = new OleDbConnection(strAccessConn);
        OleDbDataAdapter myCommand = new OleDbDataAdapter(strAccessSelect, myConnection);

        // Populate the dataset with the results of the select query
        DataSet ds = new DataSet();
        myCommand.Fill(ds, sTable);

        // Update column names to include "(000s)"
        DataColumnCollection drc = ds.Tables[sTable].Columns;
        DataColumn dc = new DataColumn();
        dc = drc[listBox1.SelectedItem.Text];
        dc.ColumnName = "Pop (000s)";
        dc = drc["Increase"];
        dc.ColumnName = "Incr (000s)";

        int iPrevPop = 0;
        int iCurrPop = 0;
        int iDiff = 0;
        double Pct = 0.0;
        int iCurrRow = 0;
        DataRow prevRow = null;
        DataColumn prevCol = null;

        // Iterate through the dataset row by row
        DataTable myTable = ds.Tables["states"];
        foreach (DataRow myRow in myTable.Rows)
        {
            int iCurrCol = 0;
            foreach (DataColumn myColumn in myTable.Columns)
            {
                // Column 2 value is year to year difference value
                if (iCurrCol == 2)
                {
                    if (iCurrRow == 0)
                    {
                        iPrevPop = 0;					
                    }
                    else
                    {
                        // Replace null value in dataset with population difference value
                        iPrevPop = int.Parse(prevRow[prevCol].ToString());
                        iCurrPop = int.Parse(myRow[prevCol].ToString());
                        myRow[myColumn] = iCurrPop - iPrevPop;
		    }
		}
                // Column 3 value is year to year % difference value
                if (iCurrCol == 3)
                {
                    if (iCurrRow == 0)
                    {
                        iPrevPop = 0;
                    }
                    else
                    {		
                        // Replace null value in dataset with % population difference value
                        iPrevPop = int.Parse(prevRow[prevCol].ToString());
                        iCurrPop = int.Parse(myRow[prevCol].ToString());
                        iDiff = iCurrPop - iPrevPop;
                        Pct = (double)iDiff / (double)iPrevPop;
                        int iTmp = (int)(Pct * 10000);
                        Pct = ((double)iTmp) / 100.0;
                        myRow[myColumn] = Pct;
                    }
                }

                if (iCurrCol == 1) prevCol = myColumn;
                iCurrCol++;
            }

            iCurrRow++;
            prevRow = myRow;
        }

        // Bind datagrid with dataset values
        MyDataGrid.DataSource = ds.Tables[sTable].DefaultView;
        MyDataGrid.DataBind();
    }
</script>

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<asp:DataGrid id="MyDataGrid"
    Width="360"
    BackColor="#ccccff" 
    BorderColor="black"
    ShowFooter="false"
    CellPadding=3 
    CellSpacing="0"
    Font-Name="Verdana"
    Font-Size="10pt"
    GridLines="Horizontal"
    HeaderStyle-BackColor="#aaaadd"
    EnableViewState="false"
    runat="server">

    <HeaderStyle BackColor="#00aaaa" Font-Bold="true">
    </HeaderStyle>
</asp:DataGrid>

...HTML tags...