Auckland, Wellington and the Waikato saw the biggest drops.
NZTA general manager strategy and performance Ernst Zollner said safety of older people was an emerging concern for the agency because it was the fastest growing segment of the population.
Not only would there be more of them on the road, but they would also be driving further distances than before, he said.
However, while there had been a spike in the past year, he said NZTA focused on the long-term trend which showed older driver casualties were still dropping.
AA motoring affairs general manager Mike Noon said the issue with older people involved in crashes was their fragility rather than their ability.
"What would be a relatively minor accident for a younger person can result in some serious injuries for an older person," Mr Noon said.