Year % 1991 7.52 1992 10.62 1994 12.08 1995 12.08 1996 12.4 1997 12.34 1998 12.93 1999 13.21 2000 12.7 2001 13.06 2002 12.99 2003 12.75 2004 13.24 2005 12.55 2006 13.4 2007 13.46 2008 12.78 2009 13.51 2010 12.88 2011 10.13 2012 8.37 2013 7.57 2014 7.68 2015 8.46 2016 8.81 2017 14.86 2018 13.2 2019 13.51 2020 13.51 2021 13.27