protected function updateCurrencyRates(Currency $currency)
    {
        $baseExchangeRate = $this->table[$currency->getCode()];

        foreach ($this->table as $currencySymbol => $exchangeRate) {
            $rate = $this->calculateExchangeRate($baseExchangeRate, $currencySymbol);
            $this->addUpdateExchangeRate($currency->getCode(), $currencySymbol, $rate);
        }

        $this->helper->getEntityManager()->flush();
    }