Year	Percent
1980	55.37869
1981	53.39554
1982	47.97768
1983	49.07407
1984	62.44666
1985	48.48195
1986	55.51898
1987	60.45923
1988	62.01969
1989	59.74115
1990	62.22007
1991	54.27001
1992	49.71948
1993	46.6908
1994	49.83191
1995	47.96101
1996	50.00342
1997	52.77929
1998	52.58147
1999	55.057
2000	52.97015
2001	50.86822
2002	52.56008
2003	53.18529
2004	50.56064
2005	54.65935
2006	61.13259
2007	61.09162
2008	62.37125
2009	51.62401
2010	58.21243
2011	60.09441
2012	62.46068
2013	61.29502
2014	60.56159
2015	57.24902
2016	49.69311
2017	52.01306