Count users by specific role.

Hello I am trying to count users in a specific role.
I used the example and it works fine but how would I go about just counting one specific role. In the case the role id is “rlgw”

<?php
$result = count_users();
echo 'There are ', $result['total_users'], ' total users';
foreach($result['avail_roles'] as $role => $count)
    echo ', ', $count, ' are ', $role, 's';
echo '.';
?>

Thanks in advance!.