Re: Salary increase ..
the question should be, what minimum salary increase should be the one that would make you accept a job offer? A new job offer does not automatically guarantee any salary increase, in fact it could be less than what you were making at your current job.
Like in my case, I was hired in my current company at a contract position. 1 year later, they offered me a full time position and they offered a salary that was 12% less than my contract salary. I accepted the offer as there were more benefits and full time position is more secured than a contract position.