Clean webform cache.

Generally webforms get data from cache while click on browser back button. Following code snippet will cleanout the page cache and doesn't display any previous data even clicking on browser back button.

 Response.Cache.SetCacheability(HttpCacheability.NoCache);
        Response.Cache.SetExpires(DateTime.Now.AddSeconds(-1));
        Response.Cache.SetNoStore();
        Response.AppendHeader("Pragma", "no-cache");