using System;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        var symbols = "ABCDEF0123456789".ToDictionary(c => c, c => 0);

        for (int i = 0; i < 1000; i++)

            Guid.NewGuid().ToString().ToUpper().Replace("-", "").ToList().ForEach(c => {if (symbols.ContainsKey(c)) symbols[c]++;});

​

        var ordered = symbols.OrderByDescending(d => d.Value);

        var rank = 0;

        foreach (var item in ordered)

            Console.WriteLine("Rank: " + (++rank) + " - Letter: " + (item.Key.ToString()) + " - Count: " + (item.Value));

    }

}