function getSubscribersCount($fromDate = null, $toDate = null, $mailingIds = array(), $contactIds = array(), $contactEmails = array(), $contactExternalIds = array(), $excludeAnonymousContacts = false)
    {
        $params = $this->createCountQueryParameters($fromDate, $toDate, $contactIds, $contactEmails, $contactExternalIds, $mailingIds, null);

        if (isset ($excludeAnonymousContacts))
            $params ['exclude_anonymous_contacts'] = ($excludeAnonymousContacts == true) ? "true" : "false";

        return $this->get('reports/subscribers/count', $params);
    }