The artist Luke DuBois, who presented several interesting pieces at the Aspen Ideas Festival, once did an installation that displayed the frequency with which words were used in State of the Union addresses. "The address is in many ways the best original source material for elucidating the concerns and anxieties apparent in the national zeitgeist for a given time," DuBois argued.
So he took the addresses delivered by a given president, analyzed the words that appeared most frequently, and displayed them in the style of those charts that eye doctors use to test your vision.
Here is the chart for George W. Bush's time in office:
bush admin.png

You can look at the results for every president here. The word George Washington said most: "Gentlemen."