Year	Percent
1965	0.73868
1966	0.70908
1967	0.69425
1968	0.65557
1969	0.71546
1970	0.62983
1971	0.71802
1972	0.88157
1973	0.86497
1974	0.8014
1975	0.83074
1976	0.88185
1977	0.97184
1978	1.11853
1979	1.57765
1980	1.73634
1981	2.27955
1982	2.77634
1983	3.55145
1984	6.44328
1985	6.58972
1986	4.32996
1987	4.46916
1988	4.27132
1989	4.87235
1990	3.41367
1991	2.73258
1992	2.25358
1993	1.67873
1994	1.35222
1995	1.17506
1996	1.07441
1997	1.00777
1998	0.92294
1999	0.92055
2000	0.84033
2001	1.09067
2002	1.13024
2003	0.84138
2004	0.81021
2005	0.77748
2006	0.76601
2007	0.82368
2008	0.80724
2009	0.91912
2010	0.93845
2011	0.9538
2012	0.9419
2013	0.97532
2014	0.93158
2015	0.95193
2016	0.9221
2017	0.90052