警告：单元格格式为文本或前面有撇号

I have created a XSL report using PHPExcel successfully. In that XSL report, I am displaying some percentage values with symbol %(like 70%). The problem is, cell containing the % symbol shows warning message as:

The number in this cell is formatted as text or preceded by an apostrophe.

If I select the XSL warning from XSL sheet and Convert to Number then warning has disappeared.

How to resolve (disappear) warnings from XSL report using PHPExcel?

Please help me to solve this issue. Thanks.

If you want to write a percentage value to a cell then you write that number dividedby 100, and format as a percentage

$value = 70;
$objPHPExcel->getActiveSheet()->setCellValue('A1',$value / 100);
$objPHPExcel->getActiveSheet()->getStyle('A1')
    ->getNumberFormat()
    ->setFormatCode(PHPExcel_Style_NumberFormat::FORMAT_PERCENTAGE);