Ah, the famous "spatósimo", as we call it in Greece. It was instituted several years ago (€11 for domestic and €22 for international trips, if I remember correctly) in order to partly pay for the construction of the new Athens airport. Some time ago it was revealed that Olympic Airways, as it was called then, had not been passing what they were collecting from their tickets along to the state coffers, but keeping it for themselves. Caused quite a stir at the time.