Year	Percent
1982	72.35
1983	68.92
1984	69.6
1985	68.6
1986	70.47
1987	71.48
1988	72.03
1989	70.51
1990	70.26
1991	72.54
1992	71.2
1993	72.58
1994	69.22
1995	43.24
1996	72.8
1997	53.57
1998	53.06
1999	51.44
2000	51.2
2001	51.2
2002	50.48
2003	52.67
2004	50.6
2005	52.2
2006	52.81
2007	53.07
2008	55.63
2009	54.26
2010	55.15
2011	56.59
2012	56.98
2013	59.67
2014	58.74
2015	60.56
2016	59.22
2017	59.57