About nine in 10 Americans have one of these, but a hundred years ago, only one in 10 could say the same. What is it?

About nine in 10 Americans have one of these, but a hundred years ago, only one in 10 could say the same. What is it?

About nine in 10 Americans have one of these, but a hundred years ago, only one in 10 could say the same. What is it?

Ans: A middle name.