private static function sortReports ($a, $b){
    	$a = json_decode($a, true);
    	$b = json_decode($b, true);
    	
    	if ($a['value']['optional'] == $b['value']['optional']){
    		return 0;
    	}
    	else{
    		return ($a['value']['optional'] < $b['value']['optional']) ? -1 : 1;
    	}
    }