That also depends on your body type and what sort of bone structure you have. I'm the same age and height and I have never been below 160 pounds since I was 18 and very fit. I'm at 176-178 right now and I'm trying to get down to 165 which where I was from the time I was 25.
I'm built like a running back with heavy bones so there is no way I could get down to anything less than 155 without being underweight.