Web site visitor statistics are highly arbitrary. I don't exactly know what the definition is, but I've used the statistics as delivered by 'Extreme Tracking'. Below you can find a couple of links to graphic representations of the various visitor hits to the web projects in the main menu.
Line chart of monthly number of visitors to the various sites
Pie chart of the total number of visitors per site since their inception, with percentages
Pie chart of the number of visitors last month, with percentages
