using System;

using System.Collections.Generic;

using System.Linq;

using System.IO;

public class Program

{

    public static void Main()

    {

        StreamWriter outputFile;

        outputFile = File.CreateText("population.txt");

        List<int> numberList = new List<int>();

        numberList.Add(151868);

        numberList.Add(153982);

        numberList.Add(156393);

        numberList.Add(158956);

        numberList.Add(161884);

        numberList.Add(165069);

        numberList.Add(168088);

        numberList.Add(171187);

        numberList.Add(174149);

        numberList.Add(177135);

        numberList.Add(179979);

        numberList.Add(182992);

        numberList.Add(185771);

        numberList.Add(188483);

        numberList.Add(191141);

        numberList.Add(193526);

        numberList.Add(195576);

        numberList.Add(197457);

        numberList.Add(199399);

        numberList.Add(201385);

        numberList.Add(203984);

        numberList.Add(206827);

        numberList.Add(209284);

        numberList.Add(211357);

        numberList.Add(213342);

        numberList.Add(215465);

        numberList.Add(217563);

        numberList.Add(219760);

        numberList.Add(222095);

        numberList.Add(224567);

        numberList.Add(227225);

        numberList.Add(229466);

        numberList.Add(231664);

        numberList.Add(233792);

        numberList.Add(235825);

        numberList.Add(237924);

        numberList.Add(240133);

        numberList.Add(242289);

        numberList.Add(244499);

        numberList.Add(246819);

        numberList.Add(249623);

        foreach(int num in numberList)

        {

            outputFile.WriteLine(num);

        }

        outputFile.Close();

        StreamReader txt;

        txt = File.OpenText("population.txt");

        Console.WriteLine("\nData:");

        List<int> numbers = new List<int>();

        while (!txt.EndOfStream)

        {

            numbers.Add(Convert.ToInt32(txt.ReadLine()));

        }

        txt.Close();        

​

        Console.WriteLine("The average is " + Average(numbers));

        Console.WriteLine("The greatest increase is " + GreatestIncrease(numbers));

        Console.WriteLine("The least increase is " + LeastIncrease (numbers));

    }

    private static decimal Average(List<int> population)

    {

        decimal total = 0; 

        for(int index=0; index < 40; index++)

        {

            total = total+ population[index];

        }

        decimal average = total / 40;

        return average;

    }

    private static decimal GreatestIncrease(List<int> population)

    {

        decimal k = 0;

        for(int index=1; index < 40; index++)

        {

            if(population[index]-population[index-1]>k)

            {

                k = population[index]-population[index-1];

            }

        }

        return k;

    }

    private static decimal LeastIncrease(List<int> population)

    {

        decimal o = 3185;

        for (int index=1; index <40; index++ )

        {

            if(population[index]-population[index-1]<o)

            {

                o = population[index] - population[index-1];

            }

        }

        return o;

    }

}   

​