They have several per yr, no doubt.
As for the Griffin-Jackson fight, I hope Griffin wins. Rampage throws hard punches, but a knockout over Griffin would still surprise me. Forrest can take heavy punches quite well.
I must admit though, aside from his wins over Liddell, I haven't taken much time to learn about Jackson. I know Shogun beat Jackson, but that was Pride, right? Anyway, Griffin took all Rua had, then finished him. What I like about Forrest is that he just has no reverse and no quit. Rampage has serious strength, but I'm not sure he has the agility or stamina to go to a decision. He either needs a knockout, or submission(which I don't see) or he may be beaten to a pulp. And from the little I've seen, Rampage will quit if he's taking a beating. He hangs in well for a few minutes, but then seems to just lose his heart. Maybe this time will be different, but I still think he'll need a KO and an early one, to beat Griffin. I just don't see him lasting a full length fight against someone as tenacious as Forrest Griffin.