ASP.NET MVC - Routes和UrlHelper

I have the following route

我有以下路线

routes.MapRoute(
    "GigDayListings",                                   // Route name
    "gig/list/{year}/{month}/{day}",                    // URL with parameters
    new { controller = "Gig", action = "List" },
    new
    {
        year = @"^[0-9]+$",
        month = @"^[0-9]+$",
        day = @"^[0-9]+$"
    }  // Parameter defaults
);
routes.M