The Guardian UK tracked the reading level of every State of the Union address and compiled the reading level of the speech for each president who gave one. You can take the graph and information as the reading level of the president or the reading level of his audience. In any case, the farther back you go, the better our the reading level of our citizens and president.
Not surprising, but very interesting information. Each president has a bit of State of the Union trivia next to his name. If you like history, maps and graphs, you'll enjoy this. You'll probably enjoy it more than tonight's actual State of the Union address. Unless you're going to watch Westminster's dog show! :)