Year % 1980 98.50659 1981 98.97167 1982 99.62652 1983 99.8876 1984 99.31804 1985 99.84889 1986 99.6636 1987 100 1988 95.95133 1989 100 1992 100 1993 99.1763 2008 99.61152 2009 98.3641 2013 100 2014 99.76588 2015 99.20716 2016 99.94597