KDP sales reports for June have begun appearing, and it seems that the borrow rate has gone down a little to $2.07. That’s a little less than 10% below the $2.26 rate for May, suggesting that the total number of borrows increased slightly.
The general trend seems to be for the borrow rate to hover a little above the $2 mark, having only been lower for the first few months. It’s worth noting that halfway through June, the Harry Potter books became available for Prime users to borrow. Even if (as suspected) those borrows don’t actually come out of the KDP Select fund, it still means that many Prime users are likely to be using their one borrow per month on those books rather than on works by other authors.
At $2.07, the rate for a borrow remains marginally below the royalty rate for a $2.99 book on the 70% royalty rate, which would be $2.09.