Year % 1972 9.94576 1973 10.57261 1974 9.86293 1976 10.77341 1985 87.92198 1986 90.97303 1987 90.82379 1988 88.92539 1989 85.41423 1990 85.11948 1991 90.71514 2011 78.31703 2012 75.72798 2013 72.76072 2014 70.04375 2015 73.30081 2016 88.17147 2017 73.41762