This is meant to be a rough idea of the relative popularity of guides, so I think you really should set up Google Analytics or some other tool if you want to get better stats. I haven't looked into this recently, but I think you will get overcounts using this internal tool: first, if you have tabs, I think each tab click is counted as a hit; and secondly, it is not screening out bots (which Google would do).
If you wanted to get weekly tallies, you could query against the stats table. There is a "date" column (which seems to be storing the dates in UNIX timestamps), so you could work with that. There is code you could presumably tweak in here:
alternately, you could just tweak this and
to display the weekly stats.
Still, I think using Google Analytics would be preferable. You can set that up via Admin > Edit Config > API in the SubjectsPlus backend.
Hope this helps,