This is always one of the trickier questions because you want the best compensation you can get, but you want to offer a number that isn't too high or too low. Do some research. Figure out what someone in this role can expect to make. It's okay to offer a range and to aim a little high because this can be a negotiation, but don't pitch an unreasonable number. It could turn off the interviewer, and it might demonstrate that you either don't know the industry well enough or you haven't done enough research on the company.