Program.cs

using System;
using System.Collections.Generic;

namespace ConsoleApplication7
{
    internal class Program
    {
        private static void Main(string[] args)
        {
            Static<int>.Add(1);
            Console.WriteLine(Static<int>.Count); //1

            Static<string>.Add("1");
            Console.WriteLine(Static<string>.Count); //1

            Static<int>.Add(2);
            Console.WriteLine(Static<int>.Count); //2

            Static<string>.Add("3");
            Console.WriteLine(Static<string>.Count); //2

            Static<double>.Add(3.4f);
            Console.WriteLine(Static<double>.Count); //1

            Console.ReadKey();
        }

        public static class Static<T>
        {
            public static readonly List<T> _items = new List<T>();

            public static int Count
            {
                get { return _items.Count; }
            }

            public static void Add(T item)
            {
                _items.Add(item);
            }
        }
    }
}