I had a little pre-agency binge but haven't read them all yet so I am not sure how to count

Next year, I anticipate my spending will go way down. My mom has been giving me money to buy ebooks for her and some of them, I will read, plus I have a huge backlog to get through, plus I get review books for my blog, plus I am just very cautious with new authors, plus I am no longer playing the Fictionwise micropay game and buying stuff I might not like etc.
The other thing is, I track by money spent divided by books read, and that includes the cost of devices. So I don't just keep a straight dollars spent accounting, because the stats take into account amortization from free books, library books etc. and only count completed books. Going by that number, I am at about $8 a book, which is satisfactory to me and a much more useful number than simply saying 'I spent x dollars on books this year.' Even so, I am anticipating halving my total next year.