How much revenue do academic authors make on their published books? Is there any dataset that look at how much revenue academic authors make on their published books?



I am aware of the question How much do Springer-Verlag authors make per book sold? but answers there focused on royalties (i.e., data on number of sold books is missing), and the question was on Springer-Verlag only.

I am most interested in the computer science field (machine learning and natural language processing in particular), but I am curious about other fields as well. I am most interested in the United States but curious about other countries as well.
I co-authored a research monograph in a rather specialized area of applied mathematics.  I have received about $300 in royalties over several years.  I think this is typical.

For most authors, the important consideration is not how much money they will make, but how effectively the publisher will be able to distribute the book.  This usually means going with a well-established publisher.  I know some highly-respected authors that also shop around to find the publisher that will distribute their book for the lowest reasonable price.