NBER Working Paper No. 19775
---- Acknowledgements -----
We have benefited from comments made by participants at several seminars and excellent research assistance from Brian Feld, Manuel Puente, Jennifer Sturdy and Paul Wassenich. The conclusions presented in this paper are those of the authors alone, and the authors have no financial or material interests in the results. The views expressed herein are those of the authors and do not necessarily reflect the views of the National Bureau of Economic Research.