Nil?
Then why does the German autobahn, where there is no speed limit and people routinely drive 200 MPH+, have a much lower fatality rate than US highways?
HHHMMMMmmmmm?
Because driving is the one thing the Europeans are by far more superior than us Americans. 98% (A low estimate) of American drivers just flat out suck and have no business being on the road.
And almost every state/region has it's unique incompetence. Here in New Jersey NOT ONE moron can grasp the simple concept that when going up a hill in order to maintain the same speed you have to press the gas pedal down a little harder, So on the slightest grade (NJ ain't exactly the Rockies) on 55 & 65 mph highways the idiots here will slow down into the 30s & 40s.
In Connecticut (BY far the worst drivers in the country) slightest curve in the road results in an immediate slam on the brakes and Lanes? What are they? (And no I don't mean Ct. drivers just change lanes without signaling they have a tendency wander out of their lane without realizing it)
In the Catskills it's "The speed limit is not 55 anymore?" and Pennsylvania it's "Slower traffic keep right - What's that?".
And I can go on & on.