ACC has shelled out almost $100 million for the treatment of sports-related concussion injuries over the past five years - with rugby by far the biggest contributor to the cost.
In statistics provided to the New Zealand Herald, ACC has revealed that nearly a fifth of the cost here comesfrom those playing the national game.
The release of the figures comes as former rugby stars consider claims against the game's authorities for alleged negligence around head injuries.
As many as 70 former rugby players could have contributed to the action, including several former All Blacks, whose lives have been affected.
The scale of the concussion issue in New Zealand is highlighted by ACC data which shows taxpayers footed $94.7m for 39,855 active claims from 2015 to 2020.
Rugby union-related injuries made up a third of the claims for a payout of $17.7m.
The majority of claims were for teenagers, predominantly those aged between 15 and 19 years old.
Former All Blacks loose forward Geoff Old has been in contact with the lawyers filing the suit, having recently lost a battle with ACC to have his condition recognised and covered.
Old's wife, Irene Gottlieb, describes him as a functional adult who needs "childlike care".
Old - who played 17 matches for the All Blacks between 1980 and 1983 - now believes he lives with CTE as a result of "untreated head knocks and no recovery".
CTE can only be definitively diagnosed post-mortem.
Old made a claim for injuries suffered playing rugby between 1972 and 1985, which ACC turned down in December 2017.
Judge Chris McGuire heard an appeal in October but the evidence presented could not prove Old had CTE on the balance of probabilities, the judge ruled.
He lives with constant headaches, is sensitive to light, has mood swings, has blackouts, and often forgets what he is doing.
He also can't remember the day he got married or anything from his time on the rugby field.
In 2016, Williams was found guilty of tax evasion and sentenced to three years, 10 months' prison.
The sentence was effectively reduced on appeal a year later to time served when the full extent of his cognitive problems was revealed.
The ACC data revealed rugby union, football, cycling, rugby league, and horse riding were the five sports with the most active claims against their name.
However, while football was the second-highest for claims, it had nowhere near the same number rugby union had at only 3382 - 9254 short.
Cycling had the second-highest payouts after rugby union, with $10.7m to 2660 claims.
The data also shows 15-to-19-year-olds sustained the most number of new concussion-related claims during the same time frame with 12,659.
ACC head of injury prevention Isaac Carlson says they have been working closely with sports partners to develop concussion protects and stand-down policies.
The agency is also focused on educating players, coaches, and volunteers about ways to prevent and deal with a concussion.
"Concussion can happen to anyone, at any age and in any environment," he said.
"You don't even need a hit on the head, or to lose consciousness. It can be caused by a simple blow to the body that causes the head to rapidly move back and forth."
Number of active concussion-related sports claims and total costs between 2015 and 2020
Rugby Union: 12,636 claims, $17,796,988
Football: 3382 claims, $4,536,135
Cycling: 2660 claims, $10,782,268
Rugby League: 2275 claims, $7,068,785
Horse Riding: 1834 claims, $7,907,986
Skiing - Snow: 1683 claims, $4,704,455
Snowboarding: 1442 claims, $1,964,921
Hockey: 1235 claims, $1,882,901
Mountain Biking: 1049 claims, $4,771,546
Basketball: 1015 claims, $1,090,282
Netball: 910 claims, $1,757,577
Skateboarding: 577 claims, $1,340,001
Trail Biking, Motocross: 564 claims, $1,355,380
Scooter: 514 claims, $581,158
Boxing: 491 claims, $977,869
Touch Rugby: 462 claims, $433,185
Motorcycling: 403 claims, $4,517,462
Martial Arts: 400 claims, $386,107
Surfing: 353 claims, $1,173,975
Outdoor Cricket: 298 claims, $845,819
Swimming: 289 claims, $1,667,199
Ice Skating: 282 claims, $1,429,494
Fitness Training/Gym: 280 claims, $318,570
Motor Racing: 270 claims, $1,695,907
Dancing: 266 claims, $1,262,224
Swimming - Pool: 245 claims, $304,646
Boating: 190 claims, $1,114,156
Softball, Baseball: 158 claims, $389,101
Waterskiing: 144 claims, $921,223
Gymnastics: 140 claims, $247,431
Other: 3408 claims, $9,490,033
Total active claims: 39,855 Total $: $94,714,778
Number of new concussion-related sports claims by age between 2015 and 2020
00-04: 250
05-09: 1903
10-14: 9702
15-19: 12,659
20-24: 6049
25-29: 3698
30-34: 1873
35-39: 1205
40-44: 989
45-49: 855
50-54: 672
55-59: 483
60-64: 314
65-69: 209
70-74: 147
75-79: 65
80+: 49
Total new claims: 41,122
• The number of total new concussion-related claims and active claims is not the same. Active claims are being paid out. Data provided by ACC.