The industry's peak ACT advocacy body said the figures supported its calls for the ACT government to hold onto surrendered taxi licences.

Canberra Taxi Industry Association executive director Tony Bryce said drivers were being affected by the same economic pressures hitting other businesses in the city.

"Like the drop in airport numbers, they've been down three per cent [annually in recent years] and that directly impacts taxis.

"I've got no evidence, but I think that the taxi industry ebbs and flows with general business and attitude around town, and if people are apprehensive if they've got a job next week their inclination to take a taxi is affected."

"It is a concern, because it means two or three jobs each day to a taxi, and that's their takehome pay."

Aerial Capital Group, which owns about 90 per cent of the city's taxi licences, had 1.8 million jobs last year. If the remaining 10 per cent of cabs had equivalent figures, there were about two million trips taken - down from 2.34 million in 2013.

There has not been a year with less than two million trips since before 2004.

Canberra Airport's passenger numbers have fallen 14 per cent since 2010.

Mr Bryce, who is also an Aerial director, said the figures meant plate releases were not warranted.

"We'd like to see evidence that workload has increased before any more plates were released," he said.

"We suggest when business does turn we release them intermittently, rather than all at once, which would flood the market and turn the wheel back around."

Attorney-General Simon Corbell has previously said the government was still considering what to do with the 50 licences it holds.