Year % 1989 31.64 1990 23.27 1991 19 1992 20.37 1993 9.06 1994 8.66 1995 9.02 1996 10.34 1997 10.26 1998 12.9 1999 11.22 2000 12.23 2001 11.74 2002 10.86 2003 10.83 2004 9.13 2005 7.97 2006 7.77 2007 7.83 2008 7.89 2009 8.04 2010 7.95 2011 8.18 2012 8.36 2013 9.77 2014 8.5 2015 8.6 2016 8.49 2017 8.54 2018 8.54 2019 8.48 2020 8.58 2021 8.41