How many books in the world?

Google estimates 129,864,880. Though their definition of book is quite broad.

If we generously assume a person could read 1 book per week from age 10 to 100, you will read less than 5000 books in a lifetime—0.004% of them.

A musing I have had on occasion is: what if library (non-fiction) books were modified such that every errant statement was deleted? What would the books look like? Which ones would have a greater amount of white space than words? Which would be practically empty? I imagine dictionaries and books on mathematics would remain mostly unchanged.