The responsibility for discussion papers lies solely with the individual authors. The views expressed herein do not necessarily represent those of IWH. The papers represent preliminary work and are circulated to encourage discussion with the authors. Citation of the discussion papers should account for their provisional character; a revised version may be available directly from the authors.Comments and suggestions on the methods and results presented are welcome.IWH Discussion Papers are indexed in RePEc-EconPapers and in ECONIS.