Year	Percent
1960	3.55314
1961	3.43125
1962	3.34069
1963	3.30585
1964	3.2694
1965	3.22389
1966	3.18471
1967	3.13567
1968	3.06933
1969	2.97443
1970	2.86799
1971	2.74643
1972	2.6501
1973	2.55693
1974	2.47622
1975	2.40631
1976	2.33851
1977	2.2759
1978	2.23019
1979	2.20315
1980	2.19145
1981	2.17953
1982	2.07915
1983	1.71374
1984	1.74338
1985	1.77678
1986	1.81186
1987	1.83876
1988	1.84731
1989	1.83345
1990	1.80102
1991	1.76379
1992	1.77502
1993	1.93271
1994	1.88129
1995	1.82746
1996	1.77068
1997	1.71555
1998	1.66176
1999	1.61433
2000	1.56814
2001	1.52315
2002	1.43112
2003	1.18772
2004	1.16596
2005	1.14583
2006	1.132
2007	1.11455
2008	1.09495
2009	1.06695
2010	1.03473
2011	1.00375
2012	0.97297
2013	0.94672
2014	0.92524
2015	0.90698
2016	0.89553
2017	0.88396