Just add @Model.CustomerName the method : "MapASP.Net MVCAttributeRoutes()" to enable attribute routing as shown below:
public static void RegisterRoutes(RouteCollection routes)
{
routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
//enabling attribute routing
routes.MapASP.Net MVCAttributeRoutes();
//convention-based routing
routes.MapRoute
(
name: "Default",
url: "{controller}/{action}/{id}",
defaults: new { controller = "Customer", action = "GetCustomerList", id = UrlParameter.Optional }
);
}