1. Department of Economics, University of Illinois at Urbana-Champaign, 214 David Kinley Hall, 1407 West Gregory Drive, Urbana, IL 61801 (email: )
2. Department of Economics and Public Affairs, Princeton University, 185A Julis Romo Rabinowitz Building, Princeton, NJ 08544, Center for Health and Well-Being, and NBER (email: )
3. Department of Economics, University of Chicago, 1126 East 59th Street, Chicago, IL 60637, the Energy Policy Institute at Chicago, and NBER (email: )
4. Department of Applied Economics, Sloan School of Management, Massachusetts Institute of Technology, 100 Main Street, Cambridge, MA 02142, the Center for Energy and Environmental Policy Research, and NBER (email: )