用c#制作hashtable实例，内涵多名学生姓名和成绩，怎么输出所有学生的成绩总和？

class Program
{

    public static void Main(string[] args)
    {
        Hashtable h1=new Hashtable();
        h1.Add("李明","100");
        h1.Add("张三","90");
        h1.Add("李四","80");
        h1.Add("王五","85");
        h1.Add("黄六","94");
        h1.Add("郭七","60");
        foreach(DictionaryEntry i in h1)
        {   
            Console.WriteLine("姓名:"+i.Key+"  成绩:"+i.Value+" ");
        }