2001 72.2 2002 71.8 2003 71 2004 69.5 2005 66.7 2006 62.8 2007 57.7 2008 48.8 2009 42.4 2010 42.5 2011 37.2 2012 39.6 2013 39.6 2014 40.1 2015 39.6 2016 38 2017 37