Does not seem excessive, from 160K to 100K is about right, but IMO it will start to slow down now.
This is from redbook - sell prices, forget about the advertised prices: $100,100 - $108,800 for 09' premiums.
My guesses, as good as any - 100-110K for a 3 year old one, maybe 90-95k for a 4 year old one, 85k for a 5 year old one, until they bottom out around 60-65k for a 10 year old examples. If there is no successor, R36, then I'd expect them to bottom around 75-80K.