private function writeRows(PHPExcel_Shared_XMLWriter $objWriter, PHPExcel_Worksheet $sheet)
    {
        $number_rows_repeated = self::NUMBER_ROWS_REPEATED_MAX;
        $span_row = 0;
        $rows = $sheet->getRowIterator();
        while ($rows->valid()) {
            $number_rows_repeated--;
            $row = $rows->current();
            if ($row->getCellIterator()->valid()) {
                if ($span_row) {
                    $objWriter->startElement('table:table-row');
                    if ($span_row > 1) {
                        $objWriter->writeAttribute('table:number-rows-repeated', $span_row);
                    }
                    $objWriter->startElement('table:table-cell');
                        $objWriter->writeAttribute('table:number-columns-repeated', self::NUMBER_COLS_REPEATED_MAX);
                    $objWriter->endElement();
                    $objWriter->endElement();
                    $span_row = 0;
                }
                $objWriter->startElement('table:table-row');
                $this->writeCells($objWriter, $row);
                $objWriter->endElement();
            } else {
                $span_row++;
            }
            $rows->next();
        }
    }