What's the max percent you would ask for a raise at an annual review?

- I've been with the company four years next month. Two years in this department.
- standard annual raises have always been only 2.5%.
- would it make a difference if a friend had casually offered you an in on her unit for the same amount you'd be asking from current company? (I don't want to switch jobs right now...)

I've never asked for a raise before! I have always just accepted what was offered to me.