The 20 best-selling Amazon books from 2015.

The summer break is a time to hang out with family, relax, sleep in and eat too much ice cream.

But more importantly, it’s a prime opportunity to catch up on all the books you didn’t have time to read throughout the year (despite your good intentions).

If you haven’t sorted out your summer reading stack yet, you’re about to get all the inspiration you need because online store Amazon has released its list of best-selling books from the past 12 months.

Amazon’s 2015 best-sellers

1. The Girl on the Train by Paula Hawkins

A psychological thriller about Rachel Watson, a woman who witnesses something shocking during her daily train commute and after notifying police, becomes involved. According to just about everyone, it’s on par with Gone Girl.

2. Grey: Fifty Shades of Grey as Told by Christian by E.L. James

As if the original trilogy wasn’t enough to satiate Fifty Shades fans, E.L. James released a “retelling” of her erotic (hmm) love story — this time, from the perspective of Christian Grey. It was even released on the character’s birthday.

3. Go Set a Watchman by Harper Lee

Set 20 years after the beloved To Kill a Mockingbird, Lee's sequel follows "Scout" Finch as she returns home to visit her father Atticus — and learns some uncomfortable truths (as already discussed) about her loved ones.

4. The Nightingale by Kristin Hannah

This story follows two sisters in wartime France: Vianne Mauriac, who is forced to take an enemy into her home after the Nazis invasion; and Isabelle, who joins the Resistance after falling in love with a partisan who betrays her.

5. Memory Man by David Baldacci

A thriller focused on Amos Decker, who works with investigators to find his family's murderer. Aiding him is the photographic memory he gained from a football injury that had ended his career.

6. Make Me: A Jack Reacher Novel by Lee Child

Yes, this is the same Jack Reacher played by Tom Cruise on the big screen. In the 20th book of the popular series, Reacher finds himself in Mother's Rest, a tiny town filled with secrets.

Adult colouring books aren't the only 'mindfulness' tactic. Here, Paper Tiger demonstrates an easy meditation. (Post continues after video.)

7. Rogue Lawyer by John Grisham

Love legal thrillers? Here's one for you: Sebastian Rudd is a street lawyer who defends troubled clients his peers would typically avoid because he hates injustice and believes everyone deserves a fair trial.

8. The Girl in the Spider's Web by David Lagercrantz

The latest installment of the late Stieg Larsson's Milennium series, this story follows hacker Lisbeth Salander and journalist Mikael Blomkvist as they team up yet again to chase a secret people are prepared to kill to protect.

9. Dead Wake: The Crossing of the Lusitania by Erik Larson

A non-fiction title about the sinking of the England-bound Lusitania ocean liner by a German torpedo during World War One.

10. Silent Scream by Angela Marsons

Kim Stone is a detective investigating a series of murders — but to find the perpetrator she needs to confront her own demons. If you love this book, good news — it's part of a series.

11. 14th Deadly Sin (Women's Murder Club) by James Patterson with Maxine Paetro

Of course a James Patterson book would make the list. This collaboration with Maxine Paetro follows Detective Lindsay Boxer as she tracks down a gang dressed as San Francisco cops who are ransacking the city and murdering its residents.

12. Old School: Diary of a Wimpy Kid Book 10 by Jeff Kinney

Need a stocking stuffer for the kid in your life? This is the tenth installment of the Wimpy Kid series, and this time Greg is grappling with a new challenge: a town-wide technology ban. Topical. (Post continues after gallery.)

13. Enchanted Forest: An Inky Quest and Coloring Book by Johanna Basford

Who says enchanted forests and castles are just for kids? Basford's book has been hugely popular with adults (our own Carla GS included) who use colouring in as a way to de-stress and practice mindfulness.

14. The Wright Brothers by David McCullough

Here's one for the dads out there. This biography of Wilbur and Orville Wright explores who the brothers really were and how they managed to change history. Possibly a good plane read... or perhaps not.

15. Adult Coloring Book: Stress Relieving Patterns by Blue Star Coloring

As the title suggests, this is a colouring book designed to soothe your stress with intricate, beautiful patterns.

16. The Liar by Nora Roberts

Shelby Foxworth is devastated by the death of her husband... until she learns he was a con man, an adulterer, and (you guessed it) a liar with multiple IDs. And the danger has only just begun.

17. Luckiest Girl Alive by Jessica Knoll

Just one of the books on this list being turned into a movie, Knoll's novel follows the glamorous, successful Ani FaNelli whose perfect life belies a secret from her past that threatens to destroy everything.

18. The Crossing by Michael Connelly

The latest installment of the Harry Bosch series follows the character as he begins an investigation as a favour to his brother in law, but begins to question himself as the case progresses.

19. The Stranger by Harlan Coben

Here's another one for the thriller fans: The Stranger follows, well, a stranger who appears out of nowhere and starts a chain of events and conspiracies that threaten to destroy protagonist Adam Price's life.

20. A Spool of Blue Thread by Anne Tyler

Rounding out the top 20 is this inter-generational story of love, secrets and shared stories, beginning with Abby and Red Whitshank falling in love in July 1959.

What was your favourite book of 2015?