Thomas Steger University of Greifswald   Department of Economics Friedrich-Loeffler-Strasse 70 Greifswald, 17487 Germany   steger@wifa.uni-leipzig.de   http://www.rsf.uni-greifswald.de/bwl/wachstum/steger_.html           JEL Areas: E2 : Macroeconomics: Consumption, Saving, Production, Employment, and Investment: General (includes Measurement and Data) O3 : Technological Change; Research and Development: General