I found this in the Guardian. I wonder if the same statistics apply to US libraries? From the article:
One in five Welsh language books stocked in Cardiff Central Library are never borrowed, new data reveals.
Following comments made on this article I decided to look into whether claims Welsh books were taking up space on Cardiff's libraries were true.
Cardiff Council informed me breaking down the information for every library in the city would take too long – so I decided to focus my freedom of information request on Cardiff Central Library.
Out of 6,717 Welsh language books held in Cardiff Central Library, 1,507 had never been borrowed (22%).
Out of 99,068 English language books held in the library, 9,731 had never been borrowed (9.8%).
The total percentage of books never borrowed from Cardiff Central Library (both languages) is 10.6%.