Year % 1985 73.83499 1986 74.05284 1987 74.91202 1988 73.64376 1989 74.51486 1990 76.63284 1991 78.17966 1992 80.15927 1993 80.02259 1994 81.70803 1995 84.31033 1996 85.0049 1997 85.10114 1998 85.24395 1999 86.02671 2000 86.41724 2001 87.89899 2002 88.15334 2003 88.33111 2004 88.39463 2005 89.36184 2006 90.44382 2007 90.63892 2008 90.627 2009 90.57042 2010 90.57946 2011 90.84898 2012 89.71412 2013 89.52445 2014 89.71521 2015 90.33001 2016 90.02481 2017 90.51972