Mostly young people, would be my guess! They've not learned to read while still graduating from high school. The dumbing down of America. One student at a time!
Today, I was substitute teaching in a high school considered one of the better ones in the district. One US History class for junior over which I presided was taught by a student teacher. However, when she asked the students if someone would define double jeopardy, not a hand went up. One kid sitting next to me remarked that he thought it was some sort of game. I told him that he ought to know what it is, since protection from double jeopardy is one of the rights he enjoys because he's an American.
The teacher explained the concept of double jeopardy and chose some good examples. However these kids, who will reach voting age in mere months, appear to have a lot to learn before they can vote intelligently.