The "raw" data in the user table is just the activity before it is divided by the max possible, and the data in the user table is only valid for users whose posts have been viewed today, which is why I have to calculate the activity of the entire board at the same time for the stat hack.

Doing back-activity for a single user for a limited period isn't that bad, the main problem there is that I know absolutely nothing about using GD to output a reasonable-looking graph.