My original itinerary was jfk-lis-ath-cai-zrh-pvg-icn-sfo, and the tax was $1700! I tried using ANA website and added up each segment myself and it was way less than that. I still dont understand why. I checked ITA, the segment from JFK to LIS was around $700. I played around and found that YYZ-LIS was around $400, JFK-WAW was $1200!. Probably it is higher tax from US to Europe?