Year	Percent
1983	90.62185
1985	91.83878
1987	88.05609
1988	89.72358
1989	89.66617
1990	88.5445
1991	90.0805
1992	91.00005
1993	91.07681
1994	90.19669
1995	89.76805
1996	90.86214
1997	90.70959
1998	91.42955
1999	91.11001
2000	91.13496
2001	91.05693
2002	91.29797
2003	92.18728
2004	91.17216
2005	91.0072
2006	90.83091
2007	90.69132
2008	90.6105
2009	90.21179
2010	89.37931
2011	89.04371
2012	88.91672
2013	88.19673
2014	87.86162
2015	87.29296
2016	87.29412
2017	87.3369