Amazon’s Kindle certainly seems to be dominating the e-reading space in many countries, but it’s perhaps its publisher deals that helps it truly stay ahead of the game.

In a statement today, Amazon said that Kindle Exclusives accounted for 16 of its top-100 best-selling (paid) e-books last month. These 16 books, which don’t take into account ‘borrowed’ or ‘free’ books. Amazon also noted that all the books are available for Kindle-owning Prime members  to borrow for free.

Under normal lending rules not all Kindle books can be borrowed, it is up to the publisher or other rights-holders to determine which titles can be lent. Eligible Kindle books can be loaned once, and for a period of 14 days.

However, Amazon says that more than 100,000 books are now available in the Kindle Owners’ Lending Library, (up from 75,000 in January) which lets Prime account holders borrow one book a month for free, and with no due dates.

Screenshot 21 520x255 Amazon says its Kindle Owners’ Lending Library drives 229% more sales in backlist e book titles

Amazon says the vast majority of these titles are exclusive to Kindle and published using Kindle Direct Publishing (KDP) – a self-service platform for independent authors and publishers. When KDP authors choose to participate in KDP Select, their books are automatically included in the Kindle Owners’ Lending Library.

“In March, each time Kindle owners borrowed a KDP Select book from the lending library, the author received $2.18, leading to significant increases in income for independently-published authors,” says Amazon. “One example is Martin Crosbie, the independent author of ‘My Temporary Life.’ After enrolling the book in the Kindle Owners’ Lending Library in February, he earned over $45,000 in one month from paid sales and loans combined – a huge increase from the $100 he earned the prior two months when his book was not enrolled in the program.”

Amazon also added that early sales data indicates that being included in the Kindle Owners’ Lending Library increases customer purchases of authors’ work too, noting that in the case of Suzanne Collins’ Hunger Games trilogy, 24% of customers who borrowed ‘The Hunger Games’ bought ‘Catching Fire’ and 24% bought ‘Mockingjay,’ despite the entire series being available to borrow for free in the Kindle Owners’ Lending Library.

“Since the launch of the Kindle Owners’ Lending Library in November 2011, the paid retail sales of backlist trade titles in the library have seen 229% higher growth than corresponding titles that are not enrolled,” added Amazon.

So it seems the free exposure offered to authors through the lending library is helping some gain sales through the back door for their other titles.