All the talk about UA's rumored pending service overhaul caused me to wonder how many times an airline like United typically changes an plane's interior over the life of a plane. Approximately how long have the various seating types been around? For example, the current 737 Y seats, the current Recaro Y seats, current C seats, First Suite seats, etc. -- I'm assuming all the foregoing examples with the exception of First Suite seats were installed on the aircraft when UA acquired them, correct?