Year	Percent
1976	57.41187
1977	59.19636
1978	55.32844
1979	54.1964
1980	61.16651
1981	54.95572
1982	49.7611
1983	46.80642
1984	51.80187
1985	55.18997
1986	53.61739
1987	62.24778
1988	69.39434
1989	71.23107
1990	72.15517
1991	66.04884
1992	62.54693
1993	64.28158
1994	65.46065
1995	61.0819
1996	64.27227
1997	66.34333
1998	66.51539
1999	67.41606
2000	61.94434
2001	62.53378
2002	58.7827
2003	55.38749
2004	56.39275
2005	65.85816
2006	68.61893
2007	65.00895
2008	64.41879
2009	56.75256
2010	62.2194
2011	65.0948
2012	65.70795
2013	61.55232
2014	62.22995
2015	58.84194
2016	53.8461
2017	55.06068