(CNN) -- Harper Lee's "Go Set a Watchman" may have been Goodreads' best fiction book of 2015.
Ta-Nehisi Coates' "Between the World and Me" may have dominated honors given to the year's literary output.
But when it comes down to what sold the most copies on Amazon.com -- the country's biggest online bookseller -- the winner is Paula Hawkins' "The Girl on the Train."
Amazon put out its list of 2015's best-sellers today, and the selection was an intriguing mix of history, potboilers and mystery, with Hawkins' debut novel -- about an alcoholic woman struggling to remember a possible crime -- at No. 1.
Second on Amazon's list is E.L. James' version of "Fifty Shades of Grey" as told from Christian Grey's point of view, "Grey."
Lee's controversial "Watchman," an early draft of what became "To Kill a Mockingbird," was No. 3. However, it was the best-selling print book, while Hawkins' tome led Kindle downloads.
Veteran best-selling authors also had their places in the top 20. David Baldacci, Lee Child, John Grisham and Nora Roberts all made Amazon's list, as did Erik Larson and David McCullough, writers of the top 20's only nonfiction works, "Dead Wake" and "The Wright Brothers," respectively.
Notably, two coloring books made the top 20, a sign that the trend hasn't flagged.
Here's the full top 20 list:
1. "The Girl on the Train" by Paula Hawkins
2. "Grey: Fifty Shades of Grey as Told by Christian" by E.L. James
3. "Go Set a Watchman" by Harper Lee
4. "The Nightingale" by Kristin Hannah
5. "Memory Man" by David Baldacci
6. "Make Me: A Jack Reacher Novel" by Lee Child
7. "Rogue Lawyer" by John Grisham
8. "The Girl in the Spider's Web" by David Lagercrantz
9. "Dead Wake: The Crossing of the Lusitania" by Erik Larson
10. "Silent Scream" by Angela Marsons
11. "14th Deadly Sin (Women's Murder Club)" by James Patterson with Maxine Paetro
12. "Old School: Diary of a Wimpy Kid Book 10" by Jeff Kinney
13. "Enchanted Forest: An Inky Quest and Coloring Book" by Johanna Basford
14. "The Wright Brothers" by David McCullough
15. "Adult Coloring Book: Stress Relieving Patterns" by Blue Star Coloring
16. "The Liar" by Nora Roberts
17. "Luckiest Girl Alive" by Jessica Knoll
18. "The Crossing" by Michael Connelly
19. "The Stranger" by Harlan Coben
20. "A Spool of Blue Thread" by Anne Tyler
The-CNN-Wire
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