Year % 1988 76.41355 1989 76.80885 1990 67.02573 1992 66.52413 1993 66.73917 1994 64.18568 1995 65.99099 1996 49.01272 1997 49.44036 1998 32.41945 1999 27.60398 2000 9.75727 2001 8.648255 2002 7.429176 2003 7.650723 2004 6.883996 2005 6.883996 2006 7.023858 2007 14.55693 2008 9.971525 2009 6.505945 2010 6.337801 2011 5.641749 2012 6.078093 2013 5.141011 2015 5.04492 2016 5.835344 2017 12.26567 2018 5.462543 2019 4.375216 2020 4.650285 2021 4.401905