I agree, always take these figures with a grain of salt - especially those that you have not formulated yourself. I have a mate that worked in the insurance industry and says, like you, he has seen graphs with a distance factor added. When this is added, apparently (as I have not seen what my mate has), the shape represents more of a U then a steady decline, as now the lack of driving elderly folk do and the amount of crashes they're in are related. To me, the U shape is logical, as most young drivers are learning to drive, and finding their limits and elderly folk are slowly losing their reaction time and focus, amongst other skills. The only reason I used the statistics above was because they were from Australia, and in all of the stats/graphs I've seen, fatality numbers decrease as the young drivers start growing up (i.e. when the OP would be legally allowed to drive their car), so I thought it would represent the OP's situation better than foreign stats.
That's just being silly The other 70% happens during those other times, it's better to do it between 9pm and 3am on Thurs, Fri, Sat nights!@!@!@