Results based on Dropdown selection of Month and Year

I am trying to display results based on both dropdown list selection.If a user selects Jan from 1st ddl and 2013 from 2ns ddl then results of Jan 2013 will be displayed to the user,everything works fine,I wanted to confirm the query that I have used is correct or not.

Store Procedure

Create proc usp_monthwisedata
@month int,
@year int
as
begin
select id,balance,datepart(mm,Date)Mnth from tblDailyReport where datepart(mm,Date)=@month and datepart(yy,Date)=@year
end

Design

<asp:DropDownList ID="ddlmonth" runat="server" 
            onselectedindexchanged="DropDownList1_SelectedIndexChanged" >
        <asp:ListItem Selected="True" Value="0">--Select--</asp:ListItem>
        <asp:ListItem Value="1">Jan</asp:ListItem>
        <asp:ListItem Value="2">Feb</asp:ListItem>
        <asp:ListItem Value="3">Mar</asp:ListItem>
        <asp:ListItem Value="4">April</asp:ListItem>
        <asp:ListItem Value="12">Dec</asp:ListItem>
        </asp:DropDownList> 

  <asp:DropDownList ID="ddlyear" runat="server" AutoPostBack="true" 
            onselectedindexchanged="DropDownList1_SelectedIndexChanged" >
        <asp:ListItem Selected="True" Value="0">--Select--</asp:ListItem>
        <asp:ListItem Value="2013">2013</asp:ListItem>
        <asp:ListItem Value="2014">2014</asp:ListItem>
       
        </asp:DropDownList>

<asp:GridView ID="GridView2" runat="server" EmptyDataText="Nothing selected" AutoGenerateColumns="False" BackColor="#DEBA84" BorderColor="#DEBA84" BorderStyle="None" BorderWidth="1px" CellPadding="3" CellSpacing="2"> <FooterStyle BackColor="#F7DFB5" ForeColor="#8C4510" /> <RowStyle BackColor="#FFF7E7" ForeColor="#8C4510" /> <Columns> <asp:BoundField DataField="Id" HeaderText="Id" /> <asp:BoundField DataField="Balance" HeaderText="Name"/> </Columns> <PagerStyle ForeColor="#8C4510" HorizontalAlign="Center" /> <SelectedRowStyle BackColor="#738A9C" Font-Bold="True" ForeColor="White" /> <HeaderStyle BackColor="#A55129" Font-Bold="True" ForeColor="White" /> </asp:GridView>

Code Behind

 protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
    {
        string cn = ConfigurationManager.ConnectionStrings["connectivity"].ConnectionString;
        using (SqlConnection connection = new SqlConnection(cn))
        {
            SqlCommand command = new SqlCommand("usp_monthwisedata", connection);
            connection.Open();
            command.Parameters.AddWithValue("@month", ddlmonth.SelectedValue);
            command.Parameters.AddWithValue("@year", ddlyear.SelectedValue);
            command.CommandType = CommandType.StoredProcedure;
            SqlDataReader dr = command.ExecuteReader();
            GridView2.DataSource = dr;
            GridView2.DataBind();
        }
    }

My concerns are:

1.Is the way of writing the Sp is correct to achieve the result.

2.Is it correct to set the onselectedindexchanged of both the ddls to 1 method i.e onselectedindexchanged="DropDownList1_SelectedIndexChanged" 

3.Over all Performance wise is it correct.

4.Any other solution is appreciated.