It very much depends on whether you have an Automatic or Manual. The Manual version is 50/50 most of the time, but has a viscous coupling center differential which will transfer power from whichever end of the car has least traction. The Automatic typically is a 90 front/10 rear and only transfers power back to the rear wheels when the front wheels slip or during heavy acceleration.

All of that info can be found online just by looking up technical information from Subaru themselves describing the all-wheel drive systems.