public function calculateTrackUsage($surveyId) {
        $select = $this->db->select();
        $select->from('gems__tracks', array('gtr_track_name'));
        $select->joinLeft('gems__rounds', 'gro_id_track = gtr_id_track', array('useCnt' => 'COUNT(*)'))
                ->where('gro_id_survey = ?', $surveyId)
                ->group('gtr_track_name');
        $usage  = $this->db->fetchPairs($select);

        if ($usage) {
            $seq = new \MUtil_Html_Sequence();
            $seq->setGlue(\MUtil_Html::create('br'));
            foreach ($usage as $track => $count) {
                $seq[] = sprintf($this->plural(
                                'Used %d time in %s track.',
                                'Used %d times in %s track.',
                                $count), $count, $track);
            }
            return $seq;
        } else {
            return $this->_('Not used in any track.');
        }
    }