Historical daily exchange-rate series from the European Central Bank (via Frankfurter), with computed summary statistics. Pass base = 3-letter ISO 4217 currency (default USD), start = YYYY-MM-DD, optional end = YYYY-MM-DD (default = latest available), optional symbols = comma-separated target codes (default all), optional amount to scale rates (default 1). Range is capped at 366 days. Returns, per target currency, first/last/min/max/mean rate plus absolute and percentage change over the window, alongside the full daily series. ECB publishes on business days only; weekends and holidays are omitted.