Nombre moyen de livres lus par an aux États-Unis 2014

La question était formulée par la source comme suit : « Now, we'd like to ask you some questions about books and reading. When we refer to books, think of books in any format - not just hardcovers and paperbacks, but electronic formats as well. How many books do you typically read in an average year? If you are not sure, please use your best estimate. »

La source ajoute l'information suivante : « Percentages may not add up to 100% due to rounding ».