About one in 10 Americans say they used one of these last year — that number was near 100% a couple of decades ago. What is it?

About one in 10 Americans say they used one of these last year — that number was near 100% a couple of decades ago. What is it?

About one in 10 Americans say they used one of these last year — that number was near 100% a couple of decades ago. What is it?

Ans: A telephone book.