Year	%
1973	72.47993
1974	74.97937
1975	79.46668
1976	75.3964
1977	78.35283
1978	69.98808
1979	77.6101
1980	78.86678
1981	79.69344
1982	82.09867
1983	83.50319
1984	83.33852
1985	86.16274
1986	85.84867
1987	85.89643
1988	86.79007
1989	88.66997
1990	87.06341
1991	89.84901
1992	89.45865
1993	89.52971
1994	89.56664
1995	89.2991
1996	89.44353
1997	89.32885
1998	89.22724
1999	90.42291
2000	90.06226
2001	91.8399
2002	92.22881
2003	92.09406
2004	91.81779
2005	91.09194
2006	91.19009
2007	91.32955
2008	91.25922
2009	91.30435
2010	90.88085
2011	90.49448
2012	87.26139
2013	88.16397
2014	88.19337
2015	88.64357
2016	89.71471
2017	90.41339