I don't know. Maybe they allocated more spots this year, but my gut tells me that Dopey really is at fault here. Last year was probably a wait and see year for many people considering Dopey. Now that they've heard stories (good and bad, but mostly good) they have decided to try it. And why only do Goofy when you can add on a couple of "easy" races and get 3 more medals out of it? I even think the majority of the people signed up for Goofy are the ones that couldn't get in to Dopey, so they took the "second best" option.
Of course, there are people who couldn't take the extra time off of work to do Dopey, or didn't want to spend the extra money, but I think that's a small percentage.