111th Congress among "oldest" in U.S. history

The Wall Street Journal has an interesting interactive graphic (see here) that shows that:

The 111th Congress, which convened in 2009, is among the oldest in U.S. history. The average age of members of Congress has risen steadily since 1981, with just a slight hiccup in the early 1990s; the rise is likely the result of a high incumbency rate, the aging of the U.S. population, and the first-time elections of older candidates.