Top 11 Book Categories on Amazon (What Types of Books Are You Reading?)

There are 32 major book categories on Amazon. I sorted them by # of titles to find out what types of books were most widely written...and presumably read. For all you other @mentalfloss knowledge junkies, here are the top 11 categories (and the top 3 subcategories for each).
  1. 1.
    Reference (13.8% of books)
    1. Foreign Language. 2. Words, Language & Grammar. 3. Almanacs & Yearbooks.
  2. 2.
    History (11.4%)
    1. World. 2. Europe. 3. Americas.
  3. 3.
    Literature & Fiction (10.7%)
    1. Literary. 2. Genre fiction. 3. Foreign Language Fiction.
  4. 4.
    Business & Money (5.8%)
    1. Economics. 2. Management & Leadership. 3. International.
  5. 5.
    Politics & Social Sciences (5.3%)
    1. Social Sciences. 2. Politics & Government. 3. Philosophy.
  6. 6.
    Science & Math (4.9%)
    1. Nature & Ecology. 2. Biological Sciences. 3. Mathematics.
  7. 7.
    Arts & Photography (4.9%)
    1. Music. 2. Photography & Video. 3. History & Criticism.
  8. 8.
    Children's Books (4.6%)
    1. Literature & Fiction. 2. Education & Reference. 3. Growing Up & Facts of Life.
  9. 9.
    Religion & Spirituality (4.5%)
    1. Christian Books & Bibles. 2. Religious Studies. 3. New Age & Spirituality.
  10. 10.
    Education & Teaching (2.8%)
    1. Schools & Teaching. 2. Test Preparation. 3. Higher & Continuing Ed.
  11. 11.
    Medical Books (2.5%)
    1. Medicine. 2. Psychology. 3. Basic Sciences.