Which ortofoto årgange cover a point (no key)

Which of the published årgange were actually flown over a point — the list a "through the years" view can offer without half its buttons producing a blank. Coverage cannot be read off the capabilities (the national layers declare the whole country regardless of where the year was flown), so this probes one tile per published year and caches the verdict per z15 tile. Metered as ONE call regardless of how many years were probed. Takes the same lon/lat (or DAWA x/y/srid) vocabulary as the other coordinate endpoints.