Year % 1991 15.62 1994 8.03 1995 11.43 1996 11.5 1997 11.7 1998 11.79 1999 13.64 2000 13.73 2001 13.45 2002 13.2 2003 13.24 2004 12.41 2005 11.21 2006 10.41 2007 10.94 2008 10.84 2009 10.84 2010 10.82 2011 10.89 2012 10.89 2013 10.65 2014 10.56 2015 10.56 2016 10.56 2017 10.37 2018 10.37 2019 10.37 2020 10.34 2021 10.34