Does anyone on this board have the official total number of visitors to the park in 2006?
Statistics like this come from the agency and usually are released well into the following year, if not the year after that.
Realize that any 'official' count is nothing more than an estimate or best guess. There is no way to account for every single person that enters the park. There is a tendency for all such counts to be somewhat inflated to 'adjust' for the ones that were missed.
How can this be? Well, consider that not everyone goes into a visitor center, where they could perhaps be counted. Also people can enter the park when the scenery taxation (that would be entry) booths are closed. When I arrive after hours and go into the visitor center the next day to get my car tag, I've never, ever had anyone ask how many rode with me.
If traffic counters are used, there is a 'people per car' factor used to determine total number of riders. The accuracy of such 'average occupancy' multipliers depends entirely upon the diligence of the people collecting the data to arrive at accurate figures. There is again a tendency to use a higher factor than is actually the case because it is very labor intensive to collect this kind of data across all seasons and use pattern situations.
Probably the most accurate indicator, but far from accounting for everyone, are the revenues collected from people who do not have some form of pass to enter the park. Those fees can be accurately tracked as a total that goes up or down each year depending upon any number of circumstances, but it in no way reflects accurately the total visitation for the park.