1. Bahrain Center for Strategic, International and Energy Studies, PO Box 496, Manama, Bahrain, and Department of Economics and Mercatus Center, George Mason University (e-mail: )
2. University of Chicago, 1126 E. 59th Street, Chicago IL, 60637 and NBER (e-mail: )
3. The University of Chicago Medicine, 5841 S. Maryland Avenue, MC 1035, Chicago IL, 60637 (e-mail: )