I'm going to say that participation in 2015 is down compared to 2014. I wasn't playing Gran Turismo before 2014's GT Academy, so I have no idea what earlier years were like. Personally, I haven't given Round 4 much effort at all. The first three rounds, I treated them like Seasonal Events - once I post a Gold time I stop. Even though I know I have absolutely no chance in hell of being a "top driver", since Round 4 is the round that counts, I was planning on running lap after lap until I knew I just physically could not do any better. That didn't end up happening. I just can't stand driving the Nissan LMP1 car for more than 15-20 minutes. I guarantee I haven't put in more than 1 hour, in total, into Round 4.