Great find, Gary! You say there are “about” 20 pages in your copy of the booklet. The full booklet has 38 pages. (Based on your picture that shows the page for stamps #29 and 30, I’m guessing that you have the full thing.)
There were also special train tickets and a plastic “credit card” collectible that went along with the booklet. I posted pictures of those a few years ago in my collection thread. You might have some of those, too, and just didn’t realize they belonged with the booklet. If interested, you can view them here:
www.elitefourum.com/t/from-the-japanime-vault-updated-october-24-2021/11101/2