How much data does turn-by-turn navigation use?

[MRW1215]

I assume using turn-by-turn GPS navigation uses my cellular data, and being on a 2GB per month plan via Verizon, that always makes me wary of using it ever. Although, to be fair, at the moment, I don't really have a need for it, but I can see myself using it in the near future.

So, let's say I use Google's Maps app for turn by turn navigation. About how much data would that use, say, per hour, or some other measurable amount of time?