I go back and forth on if its helpful to set a goal on the number of books. Sometimes its a good motivation for me. Other times its a distraction to the goals of why I read: to learn and to enjoy.

The year my son was born I spent hours everyday pushing him in a stroller to help him stop crying and give his mom a break. I read / listened to 105 books that year, which ended up being too much. I couldn't remember most of what I read / listened to. The next year I had to re-read many of the books.

The sweet spot for me is between 40 and 50, although I've adjusted my goal from number of books to subject mastery. Focusing on a subject I care about and studying books, articles, etc. on the subject has ended up being more rewarding. In addition, I have a handful of books I read simply for the joy of reading.