How many 5th grade science textbooks are printed every year?

Although the textbook industry accounts for the majority of books sales each year, the exact amount of fifth grade science textbooks published each year is not made public. The top three textbook publishers account for over 90 percent of textbook industry sales, but none of them publicly releases publishing statistics

Pearson and Houghton Mifflin do not provide a publicly available breakdown of their titles and intended student demographics. McGraw-Hill simply lists their number of textbook titles as in the thousands. As electronics become more prevalent in classrooms, textbook companies are focusing their development efforts on publishing more electronic resources and fewer physical books.