Nearly 700 people have been caught driving under the influence of drugs since anti-drug-driving laws were introduced in November 2009.
The figures have led the Automobile Association to declare an epidemic.
Topping the country's drug-driving statistics is the Bay of Plenty, where 139 drivers have been charged for driving under the influence of drugs since the law came into force.
But AA spokesman Dylan Thomsen said if police in other districts carried out the same number of tests, the results would likely be similar.
"The police in the Bay of Plenty have actually made this a focus and have been doing more tests. I would say it's a credit to the Bay of Plenty police that they are targeting the issue, but it's just the tip of the iceberg," Mr Thomsen said.
Police figures show 88 of the drugged drivers caught in the Bay of Plenty had THC (cannabis) in their system, 29 had stimulants, four had opiates, and three had sedatives.
Nationally, 453 drivers were drug tested in hospital after a crash that was deemed to be their fault and 156 were found to have drugs in their system.
Mr Thomsen said drugged driving was an epidemic. "I think when you look at the latest figures, there's no other way to describe it."
Bay of Plenty police Senior Sergeant Ian Campion said the issue was bigger than people realised.
"You only have to look at the stats," Mr Campion said. "We've got more of a problem with drug-driving than everybody perceives and, of course, the biggest concern is that even a small minority of drugs in the system coupled with alcohol can exacerbate the potential danger."
The lack of police ability to test for drug-drivers in the past might have fostered a casual attitude, he said.
People aged between 20 and 39 years accounted for more than half of those charged with drugged driving in the Bay of Plenty.
Waitemata, which had the second-highest rate, had 81 drivers charged, and 694 people were prosecuted nationwide. Most were men.