public function getSwapPercentUsed()
    {
        if ($this->getSwapTotal() !== null) {
            if ($this->getSwapTotal() > 0) {
                return round($this->getSwapUsed() / $this->getSwapTotal() * 100);
            } else {
                return 0;
            }
        } else {
            return null;
        }
    }