public ActionResult Details(string id, int?year) { var statistics = new PopulationStatistics(); var details = new CountryDetails(); var availableYears = statistics.GetAvailableYearsForCountry(id); details.Name = id; details.AvailableYears = availableYears.Select(availableYear => new SelectListItem { Text = availableYear.ToString(), Value = availableYear.ToString() }); var selectedYear = year ?? availableYears.First(); details.MalePopulation = statistics.GetMalePopulation(id, selectedYear); details.FemalePopulation = statistics.GetFemalePopulation(id, selectedYear); details.TotalPopulation = details.MalePopulation + details.FemalePopulation; return(View(details)); }