Assuming you're using SimpleXML, you can just access it as though there was a numeric array:
// The first item is this...
echo $objMyObject->groupCount;
// ... but also this
echo $objMyObject->groupCount[0];
// The 6th item would be this
echo $objMyObject->groupCount[5];
// Or you can loop over them all like this
foreach ( $objMyObject->groupCount as $i => $count ) {
echo 'The ', $i+1, 'th item is ', $count;
}