Year % 1989 10.87731 1990 10.96623 1991 11.40789 1992 11.41503 1993 11.50841 1995 9.609604 1996 9.187134 1997 8.960987 1998 8.688624 1999 7.934903 2000 7.795129 2001 7.72047 2002 7.731103 2003 6.973958 2004 5.2148 2005 5.03807 2006 4.836478 2007 5.418488 2008 4.775193 2009 4.460267 2010 4.432086 2011 4.451167 2012 4.341097 2013 4.288975 2014 4.38129 2015 4.354247 2016 4.221258 2017 4.948077 2018 4.592044 2019 4.753657 2020 4.648269 2021 4.8504