Rates are downloaded from https://www.ecb.europa.eu/stats/policy_and_exchange_rates/euro_reference_exchange_rates/html/czk.xml
<?php
use mikaelz\HistoricalEuroRates;
require 'HistoricalEuroRates.php';
$histEuroRate = new mikaelz\HistoricalEuroRates('CZK');
echo $histEuroRate->getRate('2017-05-22');
// or all rates
print_r($histEuroRate->getRates());