Hop deterioration is based on the HSI (Hops Stability Index). Most hops are between 25 and 50%. This number represents the loss of Alpha Acids (bittering compounds) in 6 months when left un-packaged at 70 F.
Vacuum packing considerably improves the AA retention, and cold temperatures are even better.
If you want to find out what you potentially lost, you can use BeerSmith, or other calculators; there are probably free on-line calculators out there. Alternatively, you can post the hop type, the original AA, storage conditions (vacuum packed) and the time and temperature, and someone will probably get you the answer.