I think you guys are missing the point.
The graph you show is kind of irrelevant. The only things we can conclude is where the major drops are showing when (what I assume to be) Seatbelt wearing became mandatory. The gentle slide after would just be general things like, safer cars, better roads, and laws to improve safety such as lower speeds.
P platers in general (this no longer includes HPI type drivers as they have a law against driving such cars) are over represented in that graph you have shown. They are the people who should be targetted in any campaigns to kerb fatalities.
Although, I do feel that recent data showing any P plate percentage of road fatalities may be skewed against the P plate drivers.
As a percentage of total drivers, P plate drivers have increased recently with the introduction of Green P plates. This has of course increased the percentage of P plate drivers over the total amount of drivers, and as such you would expect an increase in their representation on any statistical analysis.
Hoon's have been historically the younger generations. Back in the day, when it all began, the youth would modify their cars, and race on the streets. That is no longer acceptable as people expect safer driving conditions. P platers are that generation now. They want to have that same fun, but have now a lot of restrictions on them. Now that they are also a larger group than any time before.
This finally brings me back to point Jon is making.
The car of choice for that group of people right now and probably for the last 10ish years in increasing popularity are imports. It's clear when you drive around the streets and around the local traps.
Those people will be targeted for that reason, They are percieved to be part of that group of people no matter if they are or not.
I owned an import for 3yrs and in those 3yrs never once was pulled over by a cop and harrassed.