Tsundoku: a Japanese term for the habit of buying books, then leaving them unread in a pile.

1. Catch-22 by Joseph Heller

2. The Lord of the Rings by JRR Tolkien

3. Ulysses by James Joyce

4. Moby-Dick by Herman Melville

5. Atlas Shrugged by Ayn Rand

The constantly changing aspect of (not) reading books means that statistics on which ones are the most unread/least finished are impossible to nail down once and for all.

But we can see snapshots in time. Above, for example, are the top five Most Abandoned Classics as indicated by the members of Goodreads in July 2013. Below is its overall list of Most Abandoned:

1. The Casual Vacancy by JK Rowling

2. Fifty Shades of Grey by EL James

3. Eat, Pray, Love by Elizabeth Gilbert

4. The Girl with the Dragon Tattoo by Stieg Larsson

5. Wicked by Gregory Maguire

One, only half-serious, way of calculating unreadativity is the Hawking Index put together by maths professor Jordan Ellenberg, which analyses data from Kindles based upon how near the end of the book people highlighted a passage.

On this basis the top five looks more like this (at least in July 2014), with figures in brackets indicating the percentage of people who got all the way through:

1. Hard Choices by Hilary Clinton (1.9 per cent)

2. Capital by Thomas Piketty (2.4 per cent)

3. Infinite Jest by David Foster Wallace (6.4 per cent)

4. A Brief History of Time by Stephen Hawking (6.6 per cent)

5. Thinking, Fast and Slow by Daniel Kahneman (6.8 per cent)

Fifty Shades of Grey by EL James comes in at 25.9 per cent and, perhaps surprisingly, this approach also suggests that 98.5 per cent of people finished The Goldfinch by Donna Tartt.

Top unfinished bestselling books Show all 9 1 /9 Top unfinished bestselling books Top unfinished bestselling books Number 9 "The Goldfinch" by Donna Tartt was read from cover to cover with an HI of 98.5 per cent Top unfinished bestselling books Number 8 Readers had no trouble with "Catching Fire" from the Hunger Games trilogy. It had an HI of 43.4 per cent Top unfinished bestselling books Number 7 The Great Gatsby, by F. Scott Fitzgerald, hit the bestseller list again but only had an HI of 28.3 per cent cracked.com Top unfinished bestselling books Number 6 The infamous "Fifty Shades of Grey" by E.L. James is still being lapped up but not always to the end. It has an HI of 25.9 per cent Getty Images Top unfinished bestselling books Number 5 Michael Lewis' "Flash Boys" paints a damning picture of high-frequency trading. Its HI was 21.7 per cent Getty Images Top unfinished bestselling books Number 4 Facebook executive Sheryl Sandberg's self-help book "Lean In" was not living up to its title with an HI of 12.3 per cent AFP/Getty Images Top unfinished bestselling books Number 3 Unsurprisingly, people find it difficult to reach the end of Daniel Kahneman's psychology book "Thinking Fast and Slow". Its HI was just 6.8 per cent Getty Images Top unfinished bestselling books Number 2 The Hawking Index was inspired by readers' difficulty finishing Stephen Hawking's "A Brief History of Time". It was the second most 'unread' book with an HI of 6.6 per cent AP Top unfinished bestselling books Number 1 French economist Thomas Piketty's "Capital in the Twenty-First Century" is seeing thousands of people read about wealth and income equality in the West. But with an HI of 2.4 per cent, not many people are getting to the last page Reuters

Going further back, Malcolm Cowley, of The New Republic magazine, took a different approach to the issue. In 1934 he asked various well known American novelists and literary critics to suggest books that not enough people knew about.

He collated the results in two articles, “Good Books That Almost Nobody Has Read” and “More About Neglected Books”. These were F Scott Fitzgerald’s five choices (though he also mentioned the crime fiction of Raoul Whitfield):

Through the Wheat by Thomas Boyd

Sing Before Breakfast by Vincent McHugh

The Spring Flight by Lee J Smits

Miss Lonelyhearts by Nathanael West

I Thought of Daisy by Edmund Wilson

A fine place to track down forgotten books is neglectedbooks.com, which features “articles and lists with thousands of books that have been neglected, overlooked, forgotten or stranded by changing tides in critical or popular taste”.

It features long Lists of Neglected Books and a separate section on Justly Neglected ones.