Display latest (new) added rows on top of GridView in ASP.Net

I am adding multiple rows in gridview. Now i want that latest added row display on top in gridview?

private void insertbalgv()
{
    if
        (txtdno.Text != "")
    {
        Response.Write("<script language='javascript'>alert('Bale Already Dispatch');</script>");
    }
    else if
            (txtqty.Text == "")
    {
        Response.Write("<script language='javascript'>alert('Please Input QTY');</script>");
    }
    else
    {
        if (DDLitem.SelectedItem != null)
        {
            int codeitem = Convert.ToInt32(DDLitem.SelectedItem.Value.ToString());
            string Descriptionitem = DDLitem.SelectedItem.Text.ToString();

            DataTable dtgridview = ViewState["dt"] as DataTable;
            DataRow dr2 = dtgridview.NewRow();
            bool ifExist = false;
            foreach (DataRow dr in dtgridview.Rows)
            {
                if (dr["BID"].ToString() == txtsearcbn.Text.Trim())
                {
                    ifExist = true;
                    break;
                }
            }
            if (!ifExist)
            {
                dr2["Index"] = dtgridview.Rows.Count + 1;
                dr2["BID"] = txtsearcbn.Text.Trim();
                dr2["Codeitem"] = codeitem;
                dr2["Descriptionitem"] = Descriptionitem;
                dr2["QTY"] = txtqty.Text;
                dr2["BWeight"] = txtwht.Text;

                dtgridview.Rows.Add(dr2);
                ViewState["dt"] = dtgridview;
                GVbal.DataSource = dtgridview;
                GVbal.DataBind();
                BindSummaryGrid(dtgridview);
                lb.Text = "";
            }
            else
            {
                // Response.Write("<script language='javascript'>alert('Bale Already Added');</script>");
                lb.Text = "Bale Already Added";
            }
            clear();
        }
    }
}