Unopened Courvoisier FCN Exclusif

I have no idea what year this is made. It was part of my grandfather's estate. He was not much a drinker, it's been sitting on his shelf in its original box a least 20years. Anyone know how to look for the age of the bottle, please let me know. Or any information on how to identify the bottle, please let me know. It has a seal security code, as well as what I assume is a serial number scribe to the back bottom of the bottle.