public function convert_to_array($raw_data)
	{
		$xml = new \SimpleXMLElement($raw_data);
		$xml->registerXPathNamespace(
			self::XML_NAMESPACE,
			self::XML_NAMESPACE_URL
		);

		$data = $xml->xpath(self::XPATH_CURRENCY);
		$currencies = array();

		foreach ($data as $currency)
		{
			$currencies[ (string) $currency->attributes()->currency] = (string) $currency->attributes()->rate;
		}

		return $currencies;
	}