How often does MakerBot release a new version of their printers?

I know Makerbot just released the latest and greatest of their line of 3D Printers. However, I'm wondering when they will release their next generation. How long has it been between the Replicator 2 and the latest 3 MakerBot printers? Does it seem to be a yearly upgrade or longer?

Yearly (give or take a month or two).

It'll be interesting to see what they release next year. I have a feeling that there will be a lot more competition by then.