for::getSingleData

public function getSingleData()
{

	$data = parent::getSingleData();

	/** @var DropDown $whatWillCalculate */
	$whatWillCalculate = $this->getFormElement('calculate');
	$whatWillCalculateValue = $whatWillCalculate->getValue();

	switch ($whatWillCalculateValue)
	{
		case self::WHAT_WILL_CALCULATE_CONTENTMENT:
			$data['config']['unitOfMeasurement'] = '%';
			break;
	}
	return $data;
}