There seems to be a connection between having cyclists wearing helmets and the incidence of head injuries.
This is a really odd statistic to me - I had thought until reading this that NY and London where I've commuted for years in the past had reasonably good bike lanes but this would suggest the opposite.
It's either poor infrastructure or that drivers and cyclists behave differently when there is a helmet worn.
In the Netherlands, just 0.8 percent of cyclists wear helmets yet the Dutch have the lowest rate of cycling head injury, thanks to segregated cycling infrastructure. Thirty percent of journeys in the Netherlands are made by bike, he said, and 50 percent of children’s journey to school. ”The best way to deal with [the head injury issue] is what the Dutch have done,” he said. “Where you have the Highest rate of helmet use, you also have the highest rate of head injury: us and the US.