Try this
'divmain' is and ID of
<div>
tag
Control uc = new Control();
string controlname = <your Year>
switch (controlname)
{
case "1988":
uc = LoadControl("AdminDashboard.ascx");
divmain.Controls.Add(uc);
break;
case "2011":
uc = LoadControl("media.ascx");
divmain.Controls.Add(uc);
break;
}