Year Number 2004-01-01 55 2005-01-01 55 2006-01-01 53 2007-01-01 53 2008-01-01 55 2009-01-01 54 2010-01-01 54 2011-01-01 55 2012-01-01 56 2013-01-01 57 2014-01-01 56 2015-01-01 55 2016-01-01 58