This page contains json data : https://indexes.nasdaqomx.com/Index/Weighting/NBI

I am trying to scrap that json data using the script :

$data = array('id' => 'NBI', 'timeOfDay' => 'SOD', 'tradeDate'=> date('Y-m-dTh:i:s.000'));
$data_string = json_encode($data);

$ch = curl_init('https://indexes.nasdaqomx.com/Index/WeightingData');
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "POST");
curl_setopt($ch, CURLOPT_POSTFIELDS, $data_string);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER , false);
curl_setopt($ch, CURLOPT_HTTPHEADER, array(
'Content-Type: application/json',
'Content-Length: ' . strlen($data_string))
);

$result = curl_exec($ch);
if(!$result)
curl_error($ch);
else {
echo "";
print_r($result);
exit;
}
I am getting the page content but not the json output. Please let me know, where I am wrong.