Year	Percent
1960	13.79163
1961	13.73691
1962	13.77629
1963	13.76841
1964	13.73163
1965	13.66416
1966	12.38589
1967	6.97804
1968	6.98788
1969	6.97596
1970	6.96156
1971	6.93624
1972	6.75425
1973	6.55389
1974	6.65806
1975	6.76647
1976	6.04536
1977	3.12494
1978	3.17514
1979	3.16342
1980	3.11242
1981	3.05274
1982	2.99368
1983	2.89142
1984	2.75087
1985	2.57785
1986	3.15525
1987	5.71827
1988	5.62162
1989	5.62955
1990	5.71364
1991	5.8196
1992	5.88339
1993	5.85045
1994	5.70617
1995	5.48919
1996	5.02946
1997	3.97268
1998	3.81792
1999	3.70589
2000	3.62082
2001	3.53974
2002	3.47028
2003	3.41433
2004	3.38961
2005	3.36381
2006	3.35738
2007	2.94096
2008	2.97531
2009	3.02642
2010	3.109
2011	3.19419
2012	2.7851
2013	2.83674
2014	2.85823
2015	2.85625
2016	2.8414
2017	2.83105