5 residents/year = relatively small program = lots and lots of call
To the best of my knowledge, the largest program in the US is Mallinckrodt, with 17 residents/year. 4-5/year is about as small as you'll see... I suspect this is more common at community programs. I think average ranges from 8-10 at academic centers.
Clearly, there are pros and cons of program size. A smaller program has plenty of camraderie (hopefully), but you'll probably take call sooner and more frequently than residents in other programs... beware of fourth year call when you're trying to pass the boards. It'll also be harder to schedule electives, away rotations, and vacation weeks. If one of your fellow residents needs maternity or medical leave, your schedule will be totally screwed. Although larger programs definitely have a different atmosphere, you'll have the scheduling advantages that come with it.