Hvordan kan man lave online statistik over sit website?

function logvisit() {
    clientDate = "";
    var i_today = new Date();
    if (typeof(i_today) == "object") {
        clientDate = "&ClientDate=" +i_today;
    }
        document.getElementById('logframe').src= "http://mitdomæne.dk/visitorlog.php?" +
  "Referrer=" + document.referrer + clientDate +
  "&Navigator=" + navigator.userAgent;
}

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML  4.01//EN"  "http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<title>Visitor Logging</title>
</head>
<body>
<?php
error_reporting(E_ERROR | E_WARNING | E_PARSE | E_NOTICE);
if( $fh = fopen( "../visitorlog.txt", "a+" ) )
{
  $querystring = '';
  $logtxt = "\n From: $REMOTE_ADDR";
  $logtxt .= " Host:" . gethostbyaddr($REMOTE_ADDR);
  foreach ($_GET as $key => $value) {
            if ($key != "C") {  // ignore this particular $_GET value
                $querystring .= ' ' . $key.":".$value;
            }
  }
  $logtxt .=  $querystring;
  fputs( $fh, $logtxt, strlen($logtxt) );
  echo "Log written:<br> $logtxt <br>";
  fclose( $fh );
}
?></body>
</html>