Passage: KfW is owned by the Federal Republic of Germany (80 percent) and the States of Germany (20 percent). It is led by a five-member Executive Board headed by CEO Dr. Günther Bräunig, which in turn reports to a 36 member Board of Supervisory Directors. The Chair and Deputy Chair of the Board of Supervisory Directors are the German Federal Ministers of Finance and of Economic Affairs, with the positions alternating annually between them. The chairman as of March 2018 is Peter Altmaier, Federal Minister for Economic Affairs and Energy.In 2009, Caisse des Dépots, Cassa Depositi e Prestiti, KfW and European Investment Bank founded the Long-Term Investors Club.

Question: When do they change positions?
annually