fill array with random numbers

I have a little problem. I want fill my array with 100 random numbers. The problem is i have a lot of the same numbers 2/4 of my array is 0 then 1/4 89 andso how is this possible ???

thanks for helping

public void arrayreverse()
{
    int[] arr = new int[100];
    Random r = new Random();

    for (int i = 0; i < 100; i++)
    {
        int rand = r.Next(0, 100);
        arr[i] = rand;
        Array.Sort(arr);
        Array.Reverse(arr);
        Console.WriteLine(arr[i]);
    }
    Console.ReadLine();
}