problem with get the accurate total visitors count in ASP.NET

<%@ Application Language="C#" %>

<script runat="server">

    public static int totalNumberOfUsers = 0;
    public static int currentNumberOfUsers = 0;
    void Application_Start(object sender, EventArgs e) 
    {
        // Code that runs on application startup
        Application["totalNumberOfUsers"] = 0;
        Application["currentNumberOfUsers"] = 0;
    }
    
    void Session_Start(object sender, EventArgs e) 
    {
        // Code that runs when a new session is started
        Application.Lock();
        Application["totalNumberOfUsers"] = ((int)Application["totalNumberOfUsers"] + 1);
        Application["currentNumberOfUsers"] = ((int)Application["currentNumberOfUsers"] + 1);
        Application.UnLock();

    }

    void Session_End(object sender, EventArgs e) 
    {
        Application.Lock();
        Application["currentNumberOfUsers"] = ((int)Application["currentNumberOfUsers"] - 1);
        Application.UnLock();
    }
       
</script>