I can easily believe only 10% of drivers look at the speed limit and drive that speed. But I would have thought that 70% of drivers look at the speed limit and

I can easily believe only 10% of drivers look at the speed limit and drive that speed. But I would have thought that 70% of drivers look at the speed limit and drive some safe margin over -- either +7 mph, or +15 mph. This behavior would be driven by the size of the speeding ticket. Hard for me to believe that none of those people speed up when the speed limit goes up 10 mph.