Year	Percent
1983	70.26642
1984	72.24107
1985	71.9638
1986	73.69737
1987	75.23285
1988	73.07578
1989	68.21071
1990	71.25984
1991	70.41067
1992	70.33642
1993	70.55518
1994	67.45666
1996	65.16714
2002	63.0874
2003	62.68805
2004	61.65361
2005	64.83454
2006	65.44807
2007	66.46873
2008	68.1077
2009	67.0175
2010	69.54509
2011	68.48731
2012	69.05201
2013	69.16188
2014	69.87396
2015	68.23117
2016	68.96382
2017	68.70813