Forms Data Controls :: How To Bind Grid To Using System.Collections.Generic.List

I get this error when run the page

DataBinding: 'System.Int32' does not contain a property with the name 'item'.

protected void Page_Load(object sender, EventArgs e)
{
List<int> item = new List<int>();
{
item.Add(25);
item.Add(50);
item.Add(520);
item.Add(543);
item.Add(543);
item.Add(55);
};
GridView1.DataSource = item;
GridView1.DataBind();
}
<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="false" ShowFooter="true">
<Columns>
<asp:TemplateField HeaderText="Sub total">
<ItemTemplate>
<asp:Label ID="subTotalLabel" runat="server" Text='<%#Eval("item")%>' />
</ItemTemplate>
<FooterTemplate>
<asp:Label ID="grandTotalLabel" runat="server" />
</FooterTemplate>
</asp:TemplateField>
</Columns>
</asp:GridView>