Rank formula not working about phpspreadsheet HOT 1 OPEN

$spreadsheet = new PhpOffice\PhpSpreadsheet\Spreadsheet();
$sheet1 = $spreadsheet->getActiveSheet();
$sheet1->getCell('F9')->setValue(78);
$sheet1->getCell('F10')->setValue(82);
$sheet1->getCell('F11')->setValue(80);
$sheet1->getCell('F12')->setValue(63);
$sheet1->getCell('F13')->setValue(95);
$sheet1->getCell('F14')->setValue(86);
$sheet1->getCell('F15')->setValue(86);
$sheet1->getCell('F16')->setValue(82);
$sheet1->getCell('F17')->setValue(79);
$sheet1->getCell('F18')->setValue(73);
$sheet1->getCell('F19')->setValue(48);
$sheet1->getCell('F20')->setValue(53);

$rankFormula = '=RANK.EQ(F9,$F$9:$F$20,0)';
$sheet1->getcell('G9')->setValue($rankFormula);
var_dump($sheet1->getCell('G9')->getCalculatedValue());