That’s the only data I have to go on. You could also check the same weekend for other years on the same site. I would have guessed at least average attendance, but 2012 looks relatively quiet. I posted that link because your question often goes unanswered here. There are very few weekends that there is officially no event. I imagine the lot is not secured on a routine basis since it is also an employee parking lot, so every weekend will have some turnout even if the organizers don’t show.