Year % 1995 42.85 1996 39.52 1997 40.22 1998 44.12 1999 41.79 2000 40.2 2001 36.91 2002 38.96 2003 36.16 2004 39.72 2005 39.27 2006 39.16 2007 34.62 2008 36.08 2009 34.89 2010 36.14 2011 37.31 2012 35.49 2013 37.75 2014 34.1 2015 36.33 2016 38.07 2017 31.47