Kindle sales increased "again in 2019 thanks to independent publishing, Unlimited subscriptions and Amazon Publishing", the company claims.
Amazon, which does not disclose its figures, said: "Kindle device sales in the UK continue to show year-over-year growth, and we had our best Black Friday ever for Kindle devices."
Looking back on 2019, Amazon said there were now more than a million titles in the Kindle Unlimited service, while those who made their books available through it earned $298.9 million in the past 12 months from the Kindle Direct Publishing Select Global Fund.
"L J Ross, who publishes her books through KDP, topped the Kindle eBooks bestseller list a record seven times in 2019," added Amazon. "Thousands of independent authors who self-publish their books with KDP earned more than $50,000 from the sale of their books on Amazon, with more than a thousand passing $100,000 in royalties."
Amazon Charts, which were launched for the first time in July, showed the most read books this year were Harry Potter and the Order of the Phoenix (Bloomsbury), with Michelle Obama's Becoming (Viking) seizing the non-fiction top spot.