using System;

using System.Linq;

using System.Collections.Generic;

​

class Program

{

    static void Main()

    {

        var start_time = "08:00";

        var end_time = "09:59";

        var dictionary = CalculateTimeDifference(start_time, end_time);

        foreach (var kvp in dictionary)

            Console.WriteLine($"{kvp.Key} - {kvp.Value}");

    }

​

    static Dictionary<string, double> CalculateTimeDifference(string start_time, string end_time)

    {

        var start = DateTime.Parse(start_time).TimeOfDay;

        var end = DateTime.Parse(end_time).TimeOfDay;

        var hours = Enumerable.Range(0, 24).Select(i => new DateTime().Date.AddHours(i).ToString("HH:mm")).ToList();

        var dictionary = new Dictionary<string, double>();

        var hour_time = TimeSpan.FromMinutes(60);

        for (var i = 0; i < hours.Count - 1; i++)

        {

            var current_time = DateTime.Parse(hours[i]).TimeOfDay;

            var next_time = DateTime.Parse(hours[i + 1]).TimeOfDay;

            if (current_time >= start && current_time < end)

            {

                var minutes_difference = 0.0;

                if (next_time > end)

                {

                    minutes_difference = (end - current_time).TotalMinutes;

                }

                else

                {

                    minutes_difference = (next_time - current_time).TotalMinutes;

                }

                var current_percentage = minutes_difference / hour_time.TotalMinutes * 100;

                dictionary.Add(hours[i], current_percentage);

            }

            else

                if (current_time == end)

            {

                var end_time_difference = end - current_time;

                var end_percentage_difference = end_time_difference.TotalMinutes / hour_time.TotalMinutes * 100;

                dictionary.Add(hours[i], end_percentage_difference);

            }

            else

            {

                dictionary.Add(hours[i], 0);

            }

        }

        dictionary.Add(hours[hours.Count-1], 0);

        return dictionary;

    }

}

​