code: protected function calculatePercentageDifference(
          FosAvailabilityAlertSubscription $fosAvailabilityAlertSubscription,
          $countOfSubscriberPerProductAbstract
      ) {
          $fkProductAbstract = $fosAvailabilityAlertSubscription->getFkProductAbstract();
          $subscriberCount = $countOfSubscriberPerProductAbstract[$fkProductAbstract];
          $availability = $this->getAvailability($fosAvailabilityAlertSubscription);
  
          return $availability * 100 / $subscriberCount;
      }
docs: @param \Orm\Zed\AvailabilityAlert\Persistence\FosAvailabilityAlertSubscription $fosAvailabilityAlertSubscription
  @param array $countOfSubscriberPerProductAbstract
  
  @return float|int