The Working Paper Series of the Czech National Bank (CNB) is intended to disseminate the results of the CNB´s research projects as well as the other research activities of both the staff of the CNB and collaborating outside contributors. The Series aims to present original research contributions relevant to central banks. It is refereed internationally. The referee process is managed by the CNB Economic Research Department. The working papers are circulated to stimulate discussion. The views expressed are those of the authors and do not necessarily reflect the official views of the CNB.