I don't know how many people have attended the fair in the past, but I expect this year will set new records, for a two main reasons!
1) the economy is getting better; it may not feel like it, but people can afford to go out once in a while to the movies, out to eat, things like that. People aren't willing to spend huge amounts of money or get further in debt if they can avoid it, but things are getting better, and hopefully as a whole, we've learned how to not overspend so badly!
2) this is one of the more centralized places the fair has been in, and the closest to the center of the US it's been since FiM really started taking off. It's also far enough north that I expect we'll have a decent number of people come from Canada!