Mark Trappmann 1, 2, Ivar Krumpal 3, Antje Kirchner 4, Ben Jann 5
1 IAB, Nuremberg, Germany, 2 University of Bamberg, Bamberg, Germany, 3 University of Leipzig, Leipzig, Germany, 4 RTI, Research Traingle Park, United States, 5 University of Bern, Bern, Switzerland