~10% is more what I've seen. The biggest gain came from actually putting effort into getting lots of offers and negotiating well. This lead to an offer that was 2.75x my pay at the time. I ended up taking one that was lower (a mere 2.25x), but after stock growth, refreshers, and a base pay increase (without a promotion) that has gone up to 4x.

A 3% increase for an actual promotion is insulting. You're probably getting hosed already and could get a step function increase if you looked elsewhere and interviewed / negotiated properly. If you decide to do this, let me know, and I can give you some advice.