Year	Percent
1979	86.51761
1980	95.21863
1981	91.14256
1982	83.55015
1983	84.45042
1984	83.36176
1985	80.84172
1986	63.18908
1987	66.4964
1988	59.91435
1989	64.3678
1990	72.6022
1991	53.47594
1992	54.04232
1993	53.70045
1994	51.99299
1995	52.5861
1996	52.20705
1997	50.41224
1998	48.41761
1999	46.26879
2000	41.54187
2001	42.64775
2002	41.76901
2003	41.9763
2004	45.27354
2005	47.32394
2006	60.55197
2007	53.05205
2008	60.90678
2009	57.50077
2010	47.63498
2011	46.91436
2012	44.92564
2013	43.8913
2014	45.84196
2015	54.96877
2016	60.22952
2017	50.76026