Random rng = new Random();
Dictionary<int, UInt64> tallyCount = new Dictionary<int, UInt64>();
//Key is 1-100 and value is number of times it appears
for (int i = 1; i < 101; i++)
{
    tallyCount.Add(i, 0);
}

UInt64 totalNumbers;

Console.WriteLine("How many numbers do you require?");
totalNumbers = Convert.ToUInt64(Console.ReadLine());

for (UInt64 i = 0; i < totalNumbers; i++)
{
    int randomNumber = rng.Next(1, 101);
    tallyCount[randomNumber] += 1;
}

foreach(KeyValuePair<int,ulong> kvp in tallyCount)
{
    double percentageOfTotal = (double)kvp.Value / (double)totalNumbers;
    Console.WriteLine("{0}: {1} --> Percentage: {2}", kvp.Key.ToString(), kvp.Value.ToString(), percentageOfTotal.ToString("P4"));
}

Console.ReadLine();