foreach ($rows as $row) {
            $row['time'] = $date->createFromFormat('Y-m-d H:i:s', $row['time'])->format('Y').' Q'.floor(date('m', $date->createFromFormat('Y-m-d H:i:s', $row['time'])->getTimestamp()) / 3);
            $statistics[$row['time']]['notifications']++;
        }