In 1997, only 7% of vehicles were stolen using own keys, compared with 12% in 2001/02.
The results were outlined in a parliamentary written answer and were part of the British Crime Survey (BCS), which looked at thefts of cars, light vans, motorbikes and mopeds.
MPs heard of the key crime wave following months of calls within the fleet market for drivers to take more care of their keys.
Key theft has rocketed because new hi-tech security systems make it almost impossible to steal many makes of car the 'traditional' way. In September, stolen vehicle recovery system Tracker retrieved its landmark 10,000th vehicle.
The £80,000 Mercedes-Benz SL500 had been with its owner for just three weeks when thieves broke into his house, took the keys and drove the car away.
Using the Tracker system, police were able to recover the vehicle seven hours later.
Also in September, Subaru Impreza drivers were urged to sleep with their car keys 'under the pillow' by West Midlands Police because of key crime.
The habit of leaving the car keys lying on a kitchen table or simply tossed in a top drawer is prompting car thieves to become experts at getting into drivers' homes.
Traffic police officer Mark Crozier, of West Midlands Constabulary, said: 'One of our biggest problems now involves the theft of ignition keys from homes or public places. Getting the keys makes life a lot easier for the thief. We're trying hard to educate people to take more care of their car keys.'
In July, Tracker called on fleets to ensure their drivers were 'key aware' after it found there had been a 50% increase in vehicles stolen using their owners' keys.
A spokesman for the Home Office said: 'When you leave your car, always remove the ignition key and lock all doors. Do this all the time, even when filling up with petrol or popping into the shop. On icy mornings, never leave your car unattended with the engine running to warm it up or defrost the windows.
'Always keep your keys in a safe place, which is out of sight and away from windows and doors when you are not using your car.'
Key thefts (period and thefts of vehicles using a key as a percentage)