Year % 1995 29.94 1996 34.44 1997 29.8 1998 29.58 1999 34.94 2000 34.55 2001 33.83 2002 35.02 2003 35.27 2004 30.83 2005 31.02 2006 35.17 2007 32.85 2008 32.33 2009 31.16 2010 34.44 2011 33.75 2012 32.79 2013 33.13 2014 30.19 2015 30.68 2016 31.12 2017 35.5