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Federal Reserve Chairman Ben Bernanke (L) confers with former chairman Alan Greenspan (R). - 

This final note on the way out, which I will preface by noting that the Federal Reserve's interest rate policy of the past three or four years has been set at one quarter of 1 percent -- effectively zero, a phenomenon known to economists as the zero lower bound.

Also approaching the zero lower bound? The height of Federal Reserve chairmen. Counting back from the last four, we've got Paul Volcker at 6'7"; Alan Greenspan at 5'11"; Ben Bernanke at 5'8"; and now Janet Yellen -- President Obama's nominee the other day -- at an even 5 feet.

Follow Kai Ryssdal at @kairyssdal