Year % 1980 98.45473 1981 98.72845 1982 99.17474 1983 99.6203 1984 99.11401 1985 99.72808 1986 99.69133 1987 98.93178 1988 97.2472 1989 99.75561 1992 99.77685 1993 99.03795 2008 99.80116 2009 98.6753 2013 99.98985 2014 99.87975 2015 99.2581 2016 99.97225