<?php
// Remember create column hits with type int
// Create plugin with any name and check in events OnWebPageInit
$e = &$modx->Event;

if($e->name == 'OnWebPageInit') {
  if(!isset($_SESSION['usertype'])) {
    $_SESSION['usertype'] = '';
  }
  if($_SESSION['usertype'] != 'manager') {
    $modx->db->query("UPDATE " . $modx->getFullTableName('site_content') . " SET hits=IFNULL(hits, 0)+1 WHERE id=" . $modx->documentIdentifier);
  }
}