i don't know how many there are, but how do you plan to get them???
most of them were only released with the first press edition of an album so you won't get them by buying the album....
i remembare there being a ~on my day~ and ~off my day~ photobook (i think that's the right name....).
and if you know how i can get my hands on the GUILTY photobook i'd really like to know^^
edit: you can find the scans/list of them
here those are all of her photobook & pamphlet scans i konw of