Retrieve the data.

async def get_data(self):
        """Retrieve the data."""
        try:
            with async_timeout.timeout(5, loop=self._loop):
                response = await self._session.get(self.url)

            _LOGGER.debug(
                "Response from Volkszaehler API: %s", response.status)
            self.data = await response.json()
            _LOGGER.debug(self.data)
        except (asyncio.TimeoutError, aiohttp.ClientError):
            _LOGGER.error("Can not load data from Volkszaehler API")
            self.data = None
            raise exceptions.VolkszaehlerApiConnectionError()

        self.average = self.data['data']['average']
        self.max = self.data['data']['max'][1]
        self.min = self.data['data']['min'][1]
        self.consumption = self.data['data']['consumption']
        self.tuples = self.data['data']['tuples']