Audible is turning 20 this year, and part of the audiobook-subscription service's birthday bash involves releasing a list of its 18 most popular audiobooks of the past two decades. There are more than a few surprises on Audible's list — like the fact that The Martian by Andy Weir is the audiobook with the most five-star reviews — so let's take a look at the birthday celebration and discover what we're all listening to on our commutes.

If you have never before been a fan of audiobooks, now is the perfect time to try them out. Whether you listen on your commute, in the gym, or when you're doing chores around the house, there's probably an audiobook that's just what you need to maximize your passive productivity. So why not get started while Audible is giving its audiobooks away for free?

Audible is pairing its 20th anniversary with 20 Days of Deals for members new and old. Through Nov. 20, the audiobook platform will be giving away a ton of awesome prizes, including free audiobooks, download credits, and even T-shirts. In order to capitalize on the swag Audible is giving away this month, you will need an active account with the service, but don't worry, because users still on their 30-day free trials can still take part in Audible's 20 Days of Deals.

Free audiobooks and other merchandise aren't the only tricks Audible has up its sleeve this month. The audiobook-subscription service launched a collection of works in Mandarin on Nov. 8, and made its Chinese-language Classic Nursery Rhymes audiobook "available as a special free download," according to The Bookseller. An all-new service, Audible Romance, also debuted this month, making it easier than ever for romance-novel readers to find audiobooks that are right for them.

If you need some inspiration for your next literary listen, check out the 18 most-popular audiobooks of the last two decades below. According to Audible, these are the audiobooks your family, friends, co-workers, and neighbors go to whenever they need to listen to a good read.

The Most Wish-Listed Audiobook was 'The Girl on the Train' by Paula Hawkins, narrated by Clare Corbett, Louise Brealey, and India Fisher Fans know that The Girl on the Train is the perfect book for anyone looking to read a great mystery novel. The story follows Rachel Watson, a recently-fired divorcée whose drinking habit clouds her judgment when she inserts herself into a missing-persons investigation involving a woman with whose life she has become obsessed. Click here to buy.

The Most Anticipated Audiobook was 'Oathbringer' by Brandon Sanderson, narrated by Kate Reading and Michael Kramer Out Nov. 14, Brandon Sanderson's Oathbringer is the long-awaited follow-up to his 2014 novel, Words of Radiance. Oathbringer is the third installment of Sanderson's Stormlight Archive series, which began in 2010 with The Way of Kings. Click here to buy.

The Audiobook with the Most Five-Star Ratings was 'The Martian' by Andy Weir, narrated by R.C. Bray When an accident leaves Mark Watney stranded on Mars, the intrepid astronaut must terraform his small corner of the planet if he hopes to survive. Andy Weir's The Martian is an accessible, but mathematically accurate, science-fiction story you shouldn't overlook. Click here to buy.

The Most Bookmarked Audiobook was 'The Subtle Art of Not Giving a F*ck' by Mark Manson, narrated by Roger Wayne Mark Manson's "counterintuitive" self-help audiobook, The Subtle Art of Not Giving a F*ck, helps listeners to shed their concerns for things outside their control and focus on what really matters. Click here to buy.

The Most Repeated Listen was 'Harry Potter and the Sorcerer's Stone' by J.K. Rowling, narrated by Jim Dale It's no surprise that the first installment of J.K. Rowling's best-selling book series about the Boy Who Lived made Audible's list. Harry Potter and the Sorcerer's Stone is also celebrating its 20th anniversary in 2017. Click here to buy.

The Most Searched-For Author was Stephen King, Author of 'IT,' narrated by Steven Weber One of America's most-prolific living authors, Stephen King was the No. 1 author that Audible users searched for over the last 20 years. His 1986 novel, IT, experienced a surge in popularity this year, as Andrés Muschietti brought the story to the big screen for the first time in 2017. Click here to buy.

The Best-Selling Fiction Audiobook was 'The Help' by Kathryn Stockett, narrated by Jenna Lamia, Bahni Turpin, Octavia Spencer, and Cassandra Campbell Made into a 2011 hit film starring Viola Davis, Octavia Spencer, and Emma Stone, Kathryn Stockett's 2009 novel The Help centers on a young, white college graduate who sets out to write a tell-all based on the lives of her family's black maids in the 1960s. Click here to buy.

The Best-Selling Mystery/Thriller Audiobook was 'Big Little Lies' by Liane Moriarty, narrated by Caroline Lee Adapted into an HBO miniseries of the same name in 2017, Liane Moriarty's Big Little Lies tells the story of three mothers who find their burgeoning friendship complicated by more than a few hidden ties that bind them. Click here to buy.

The Best-Selling Romance Audiobook was 'Fifty Shades of Grey' by E.L. James, narrated by Becca Battoe Also known as the book that unseated Harry Potter from its position at the top of the book-sales charts, E.L. James' Fifty Shades of Grey follows a virginal college student who embarks on a dangerous sexual relationship with a twisted business mogul. Click here to buy.

The Best-Selling Sci-Fi/Fantasy Audiobook was 'A Clash of Kings' by George R.R. Martin, narrated by Roy Dotrice The second book in George R.R. Martin's A Song of Ice and Fire series, A Clash of Kings traces roughly the same path through Westeros as Game of Thrones Season 2. The novel was the best-selling SFF title on Audible in the service's first 20 years. Click here to buy.

The Best-Selling YA Audiobook was 'The Hunger Games' by Suzanne Collins, narrated by Carolyn McCormick Suzanne Collins' YA smash-hit about teenagers pitted against one another in a bloody, televised battle for survival was the most-popular book for adolescents on Audible. Click here to buy.

The Best-Selling Kids' Audiobook was 'Harry Potter and the Chamber of Secrets' by J.K. Rowling, narrated by Jim Dale Another win for Rowling! The second Harry Potter book, Harry Potter and the Chamber of Secrets, took top honors among Audible audiobooks for children over the last two decades. Click here to buy.

The Best-Selling Memoir/Biography Audiobook was 'Bossypants,' written and narrated by Tina Fey Fearless funny-lady Tina Fey published her first book in 2011, and it's good to see that it's still popular today. Bossypants follows the 30 Rock star from her awkward childhood through her stellar career as Saturday Night Live's first female head writer and beyond. Click here to buy.

The Best-Selling Science/Tech Audiobook was 'The Power of Habit' by Charles Duhigg, narrated by Mike Chamberlain Want to learn a new skill, train your body, or change your life? Pick up Charles Duhigg's The Power of Habit, which details how, exactly, you can teach your brain to focus on the things that matter most to you. Click here to buy.

The Best-Selling Business Audiobook was 'The 7 Habits of Highly Effective People,' written and narrated by Stephen R. Covey Succeeding in business is difficult stuff, so each of us needs all the help we can get. This best-selling book from the late Stephen R. Covey is a 1988 classic you'll want in your self-help arsenal. Click here to buy.

The Best-Selling Self Development Audiobook was 'How to Win Friends & Influence People' by Dale Carnegie, narrated by Andrew MacMillan Another classic, this time from Dale Carnegie, How to Win Friends & Influence People has been around since 1936. In its first 75 years, this book sold more than 30 million copies, so is it any wonder that listeners made it the best-selling self-development book on the Audible platform. Click here to buy.