Year % 1995 13.99 1996 25.25 1997 13.87 1998 13.85 1999 25.6 2000 23.99 2001 25.02 2002 27.91 2003 27.07 2004 25.74 2005 22.65 2006 26.59 2007 27.05 2008 25.01 2009 23.77 2010 29.04 2011 27.66 2012 27.1 2013 27.11 2014 23.88 2015 21.71 2016 22.25 2017 37.86