C# 如何在Arraylis裡找出相同的值並計算出現次數

有一個 Arraylist 裡面有值為 {1,2,3,4,5,3,10,1,2,4,12,9,4} 等數字
要一個數字只顯示一次,不重複
並計算出每個數字共出現幾次?

顯示gridview 如下

Num   Count
------------
1       2
2       2
3       2
4       3
5       1
9       1
10      1
12      1

public static void Main(string[] args)
{
    int[] iArr = new int[] { 1, 2, 3, 4, 5, 3, 10, 1, 2, 4, 12, 9, 4 };

    SortedDictionary<int, int> sDict = new SortedDictionary<int, int>();

    foreach (int i in iArr)
    {
        if (sDict.ContainsKey(i))
        {
            int value = sDict[i];
            sDict.Remove(i);
            sDict.Add(i, value + 1);
        }
        else
            sDict.Add(i, 1);               
    }

    Console.WriteLine("  Num    Count");
    Console.WriteLine(" --------------  ");
    foreach (KeyValuePair<int, int> kvp in sDict)
        Console.WriteLine("{0,4}{0,8}", kvp.Key, kvp.Value);

    Console.ReadKey();
}

Result: