Just a guess but I'm thinking the majority of us are probably between 45 and 65, of course with variables on either end. We were fortunate enough to discover SXM when we were in our late 20's so we've been luckier than most in that we've had 43 years worth of annual trips so far and still hoping for many more.
The northeast does offer a lot of nonstop flights so it would make sense a great number of regular visitors are from this particular corridor. But that said, there are a lot of Canadians who visit as well. And a lot of mid-westerners, too, but I think the northeast from New Hampshire down to the mid-Atlantic states probably are the majority because of nonstop flights and generally better pricing.
Personally, I think we're a pretty mixed bag both in ages and locations and the only real common denominator is our mutual enjoyment of this one special island. That's my story and I'm stickin' with it!!