The number of journeys is pretty irrelevant in reality though:
I want to go from London - Madrid. What is the safest way to do that? 1100 miles by car or by plane? Of course the answer is plane - because I am so much less likely to die per each of the miles travelled. In other words, 1100 hundred miles on open road would be so far above and beyond the average journey length/speed in a car, that it would actually constitute multiple journeys.
If planes were as 'safe' as cars, given the number of miles they travel, the number of deaths from planes would be through the roof.