如何使这个序列异步打印？

Question

代码输出如下：

0123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

我应该把输出混合成这样：

... 01234X5X678XX

我的意思是两个方法都应该异步启动，而不是在第一个完全完成后启动。在下面的代码中修改哪里来实现这个目标？

using System;
using System.Threading.Tasks;

namespace ConsoleApplication36
{
class Program
{
    public static void CountForward()
    {
        for (int i = 0; i < 100; i++) { Console.Write(i); }
    }

    public static void PrintX()
    {
        for (int i = 0; i < 100; i++) { Console.Write("X"); }
    }

    public async Task RunAsync()
    {
        Task t1 = Task.Run(() => CountForward());
        Task t2 = Task.Run(() => PrintX());
        Task[] tasks = { t1, t2 };
        await Task.WhenAll(tasks);
    }

    static void Main(string[] args)
    {
        Task t = new Program().RunAsync();
        t.Wait();
    }
}
}