[IDT]

My 2 cents - The number of Fatalities or even serious injuries over time can't be used as a statistic for comparisons sake. As many others have said already, examples of changes such as safer vehicles, what was bush with 110kph limit 10 years ago and full of Kangaroos and live stock is now a 50kph built up area with speed humps every 500 meters, or even heavy police presence which very rarely if ever come into calculations can have a massive effect. All accidents is the closest you will get and if you did want to break them down into major causes (the sinle biggest cause) it would be something along the lines of:
Driver Error (unintended mistake whilst not breaking the law),
Traffic system failure (i.e crap road no signage etc)
Driver Behaviour (breaking the law)
Vehicle Failure (something in the car broke)