Wrong approach: I expect 17.5 K for this job or a 10-15 percent increase from my last job.

Right approach: Do not jump at a figure when asked about expected salary. Ask the interviewer about the salary they would offer for this position.

There's a possibility that the company has fixed salary for each level. If at all you have to be the one to spell out the figure first, mention a range which is not too broad.

For e.g. "I expect something around mid-forties for this position". Keeping the range too broad may get you something towards the lower end.   _{Your Comment}