Most of those 17,000 "critical" patients were not critical at all. Last year, there was something like 18,000 admissions to the system, and that includes everything from patients that are actually critically ill, all the way down to the milk run 300km trip to the nearest CT machine.
Anyway, here are some more stats from I think 2006:
18,077 "Admissions" handled by
244 Flight Paramedics staffing
13 S-76As and
54 various fixed wing aircraft stationed at
26 different bases of operation covering
1 million square kilometers, home to
13 million people.