C＃Winforms获取发送和接收的应用程序字节

Question

我正在使用此代码来获取接收和发送的应用程序字节：

    long BytesSent = 0;

    long BytesReceived = 0;

    private void timerPerf_Tick(object sender, EventArgs e)
    {
        if (!NetworkInterface.GetIsNetworkAvailable())
            return;

        NetworkInterface[] interfaces
            = NetworkInterface.GetAllNetworkInterfaces();

        foreach (NetworkInterface ni in interfaces)
        {
            BytesSent += ni.GetIPv4Statistics().BytesSent;
            BytesReceived += ni.GetIPv4Statistics().BytesReceived;

            this.label2.Text = BytesSent.ToString();
            this.label3.Text = BytesReceived.ToString();
        }

    } 

此方法每秒调用一次。问题在于它获取所有计算机数据，而不是当前应用程序接收和发送的字节。知道是什么问题吗？