Readers have grown tired of the slew of celebrity memoirs, with titles by Stephen Fry, Graham Norton and John Cleese selling disappointing numbers, according to publishing industry experts.

Titles by Cleese and Fry sold about 60,000 copies each, according to Nielsen BookScan, which found that sales in the autobiographies and memoirs genre were down almost 4% compared with 2013.

Just five titles have sold more than 100,000 this year – two fewer than last year.

Graham Norton’s second memoir, The Life and Loves of a He-Devil, has shifted 44,000 copies, Paul Merton’s Only When I Laugh has sold 17,000, while just 8,000 succumbed to the delights of glamour model Kelly Brook’s Close-up.

Philip Jones, editor of the Bookseller, told the Independent: “In a lot of these cases, it’s their second or third book. There’s a little bit of exhaustion. You expect a big celebrity book to be selling 200,000 at this point and a lot of them aren’t.”

There’s Something I’ve Been Dying To Tell You, the autobiography by the late Lynda Bellingham has proved the most popular of 2014, selling 265,000 copies.

Guy Martin, Britain’s top motorcycle racer, has sold 168,000 copies of his autobiography, while the book by former Manchester United captain Roy Keane was bought by 149,000.

Charlie Redmayne, chief executive of HarperCollins UK, said he had slashed the number of manuscripts by celebrities that the publisher was buying.

He said such titles were risky because celebrities had to be paid large advances but their works lacked longevity in sales terms. “You’d have three weeks of sales and then it would be gone,” Redmayne told the Independent.

Jeff Bezos, chief executive of Amazon, said earlier this month that books should be cheaper because they were competing with other content that was cheaper or free. “If you realise that you’re really competing against ‘Candy Crush,’ you’d say: ‘Gosh, maybe we should think about reducing friction on long-form reading,” he told a conference in New York.

The publishing industry has been stunned by the unexpected success of the debut novel Girl Online by Zoe Sugg, better known as video blogger Zoella, which sold 178,000 copies.

However, the 24-year-old admitted she had been helped to write the book. Its acknowledgements credit Siobhan Curham, an author, and Amy Alward, editorial director at Penguin, for being with Sugg “every step of the way”.

Sugg said on social media: “Everyone needs help when they try something new. The story and the characters of Girl Online are mine.”

Andrew Franklin, publisher of Profile Books, said Girl Online was not a title he would have published despite its sales success.

“Zoella’s ghost-written confection [is] cobbled together from her dispiriting blog and her superficial life spent shopping and stressing about makeup. When there are so many great young adult books and writers, it is horrible that such effort should be put into churning out an offshoot of a blog that is essentially about … nothing,” he told the Guardian.