Year	Percent
1965	15.18024
1966	16.5763
1967	14.77156
1968	11.53937
1969	13.11225
1970	13.24718
1971	15.5937
1972	14.16453
1973	18.27888
1974	22.62588
1975	22.12173
1976	19.61963
1977	23.41551
1978	26.0745
1979	18.08502
1980	13.27379
1981	14.24415
1982	13.22141
1983	12.05514
1984	11.96045
1985	10.84582
1986	13.25117
1987	12.36145
1988	12.79175
1989	15.32756
1990	13.8129
1991	15.45549
1992	18.83297
1993	18.95763
1994	20.35812
1995	20.94422
1996	15.35496
1997	15.0832
1998	18.65106
1999	17.30148
2000	17.66906
2001	17.71407
2002	17.06467
2003	18.42923
2004	18.14074
2005	18.60471
2006	20.07546
2007	20.80003
2008	20.17265
2009	14.05462
2010	16.67162
2011	17.7899
2012	17.7519
2013	17.23385
2014	16.38435
2015	15.62824
2016	15.10651
2017	16.88944