timelines of word use frequency in the State of the Union 1900-2104: http://www.washingtonpost.com/wp-srv/special/politics/2014-state-of-the-union/language-of-sotu/
This visualization makes it easy to see trends such as the slow uptick in themes like “jobs” and “family” and the sudden introduction of contractions (thank you, Gerald Ford). “Vietnam” apparently came on the SOTU radar in 1966 and finally left again in 1998. And third person (“we” and “our”) is quite popular, though more as subject and possessive than object (“us”).