//引入命名空间
using System;

public class Example
{
   public static void Main()
   {
      // Get population data for New York City, 1950-2000.
      var population = Tuple.Create("New York", 7891957, 7781984, 
                                    7894862, 7071639, 7322564, 8008278);
      var rate = ComputePopulationChange(population);
      // Display results.
      Console.WriteLine("Population Change, {0}, 1950-2000\n", population.Item1);
      Console.WriteLine("Year      {0,10} {1,9}", "Population", "Annual Rate");
      Console.WriteLine("1950      {0,10:N0} {1,11}", population.Item2, "NA");
      Console.WriteLine("1960      {0,10:N0} {1,11:P2}", population.Item3, rate.Item2/10);
      Console.WriteLine("1970      {0,10:N0} {1,11:P2}", population.Item4, rate.Item3/10);
      Console.WriteLine("1980      {0,10:N0} {1,11:P2}", population.Item5, rate.Item4/10);
      Console.WriteLine("1990      {0,10:N0} {1,11:P2}", population.Item6, rate.Item5/10);
      Console.WriteLine("2000      {0,10:N0} {1,11:P2}", population.Item7, rate.Item6/10);
      Console.WriteLine("1950-2000 {0,10:N0} {1,11:P2}", "", rate.Item7/50);
   }

   private static Tuple<string, double, double, double, double, double, double> 
        ComputePopulationChange(
           Tuple<string, int, int, int, int, int, int> data)  
   {           
      var rate = Tuple.Create(data.Item1, 
                       (double)(data.Item3 - data.Item2)/data.Item2, 
                       (double)(data.Item4 - data.Item3)/data.Item3, 
                       (double)(data.Item5 - data.Item4)/data.Item4, 
                       (double)(data.Item6 - data.Item5)/data.Item5,
                       (double)(data.Item7 - data.Item6)/data.Item6,
                       (double)(data.Item7 - data.Item2)/data.Item2 );
      return rate;
   }           
}