Add this code to the page you want to show the user totals on:
PHP Code:
$users = $DB_site->query("SELECT usergroup.title, COUNT(userid) AS users
FROM usergroup
LEFT JOIN user USING(usergroupid)
GROUP BY usergroup.usergroupid");
while ($user = $DB_site->fetch_array($users)) {
$usertotals .= "$user[title] ($user[users])<br>";
}
...and then add
$usertotals to an appropriate template.
Easy peasy