Basically, every year should therefore bring them approximately 1000 lightyears closer to home (allowing for some detours to make the episodes interesting). But occasionally, they get ahead a lot quicker (transwarp, Kes, wormholes etc).
One more thing: as with all StarTrek series, there is the problem of converting stardates to years. Both are being used, and the years coincide with the seasons of broadcasting. However, the stardate increases by 1000 each year. For the sake of Voyagers estimated time of arrival, the years seem to be more consistent, so that's what I will refer to here.
The transwarp drive "borrowed" from the alledged USS xxx in xxx (x.x) was sayd to have brought Voyager xxx lightyears further, before they disengaged it (and apparently never dared to work on it again (hard to believe!).
In Night (5.1) Voyager used a vortex (wormhole ?) to make a jump of 2500 lightyears, or approximately 2 years closer to home. Note that before that, they had been traveling through the Void for 3 months (which is somewhat consistent with the gap in stardates between season 4 and 5).
At the end of Dark Frontier (5.8) the transwarp coil recovered from a Borg ship allowed a trip of 20000 lightyears or approximately 15 years closer to home, before the device burned out.
The USS Voyager is now still facing a journey of approx. 45 years.