I sent an e-mail to the web admin, but didn’t get a response, so here goes again…
Also, as an addendum, the “Sales Rate” sorting criteria is a bit weird too! Not sure what it’s actually supposed to be displaying, but it doesn’t seem to correspond to any expected trend. (I’d kinda figure that Arduino would be near the top of the list in Dev. Tools, but you get an oddball PIC board and some other obscure stuff…)
It seems that your “Top Sellers” category does not actually work! 
There is no significant change if you pick “Yesterday” versus "The
beginning", or any other choice. Obviously, what you sold yesterday
will be quite different that what you sold over the course of the last
month/year.
I’d assume that there will be noticeable trends, but it’s impossible
that exactly the same items appear in each list!
Your database query code needs a bit of tweaking…
If isn’t designed to work, or will never work, in the way it was
intended, then what is the duration of the existing listing criteria?
Year, month, day? (hopefully you can get it to work, as that would be
pretty cool!)
Thanks!