Hey Bud,
They wear much faster up here due to the harsh weather and road salts up here... But it depends on the vehicle and the quality of them. In my old Caravan It drove to the scrap yard 20 years later with 400,000KM on only it's second set of shocks...
"To keep a car running forever, you need to keep it running forever" Don't use it, and it will wither away.