The American Academy of Arts & Sciences has developed a Humanities Indicator prototype to track the state of the arts and humanities over time and compared to other countries. The inspiration appears to be the National Science Board's Science and Engineering Indicators.
Some of the more interesting findings from their press release:
That last data point provides a nice cautionary note about the dangers of extrapolating from pop culture trends. Given that the early part of this decade was the peak of the Oprah Book Club and the Harry Potter frenzy, I would have guessed a different trend line.
Daniel W. Drezner is professor of international politics at the Fletcher School of Law and Diplomacy at Tufts University.