As the total number of poker machines around the country has dropped, the remainder have become more profitable.
Experts in the field say the industry is squeezing out unprofitable and unpopular machines which disguises the fact they are making as much money as ever.
The numbers have been used by Prime Minister John Key to ease public concerns over a deal that could lead to SkyCity's Auckland casino getting up to 500 new pokies.
An increase in gaming machines was part of a package SkyCity has said it wants in return for building a $350 million convention centre.
Mr Key, who asked SkyCity to tender, was last night under increased pressure over his involvement after the Green Party wrote to ask Auditor-General Lyn Provost to investigate.
The party raised questions over the involvement of Mr Key and Economic Development Minister Steven Joyce in the tender process.
Mr Key had attempted to deflect criticism by pointing to a fall in the number of pokies. He said on Monday: "Back in 2005 Labour had been in office for six years and there were 25,000 pokie machines, today there are 18,000."
Statistics collected by the Department of Internal Affairs show the number of pokie machines in 2005 was actually 21,343.
However, two years earlier in 2003 the figure was 25,221.
Internal Affairs recorded $941 million being put into the machines - an average of $37,310 a machine.
Labour then championed the Gambling Act which forced a sinking lid on the number of machines.
Last year, the number of gaming machines had dropped to 18,167. The amount of money put into the machines by gamblers was $856 million - an average of $47,118 a machine.
In contrast, each poker machine at SkyCity potentially earns about $140,000 a year.
Financial information presented to SkyCity's shareholders in February showed its 1647 casino-based pokie machines at SkyCity pulled in $118 million in six months, which works out at $71,645 each for the half-year.
AUT professor Max Abbott said the drop in the number of gaming machines had not been enough to "crowd people out".
Professor Abbott, a world leader in gambling-related public health issues, said there were enough gaming machines in venues to ensure no one had to wait to gamble.
He said the gaming machines were as clustered around poor areas as they had always been.
Green Party co-leader Metiria Turei said the one-third cut in the numbers of gaming machines had barely made a dent in money gambled.
"For every machine that is added to SkyCity, 140,000 more gambling dollars will be spent by New Zealanders - money they can't afford. John Key hasn't at all considered the economic cost of problem gambling."
Ms Turei said one aspect of the complaint to the Auditor-General was lack of research around the the cost to society of new pokies at SkyCity.