How to add auto generated serial number column to Grid View?

<asp:GridView  runat="server" id="GridView1">
    <Columns>
        <asp:TemplateField ItemStyle-Height="20">
            <ItemTemplate>
                    <%#Container.DataItemIndex+1 %>
            </ItemTemplate>
        </asp:TemplateField>
    </Columns>
</asp:GridView>

Happy coding…