Year	Percent
1960	2.99015
1961	3.00017
1962	3.00381
1963	3.00233
1964	2.99581
1965	2.9809
1966	2.97065
1967	2.94734
1968	2.88103
1969	2.76405
1970	2.61894
1971	2.4659
1972	2.33766
1973	2.2542
1974	2.22853
1975	2.24232
1976	2.26219
1977	2.27118
1978	2.27856
1979	2.28057
1980	2.27675
1981	2.27437
1982	2.26886
1983	2.24804
1984	2.20869
1985	2.15648
1986	2.09986
1987	2.04573
1988	1.99459
1989	1.94874
1990	1.90627
1991	1.86511
1992	1.82172
1993	1.77413
1994	1.72116
1995	1.66552
1996	1.60833
1997	1.55522
1998	1.51173
1999	1.48059
2000	1.45766
2001	1.43738
2002	1.41372
2003	1.3847
2004	1.34789
2005	1.30562
2006	1.26283
2007	1.22175
2008	1.18056
2009	1.13963
2010	1.09909
2011	1.05834
2012	1.01799
2013	0.9796
2014	0.94378
2015	0.90978
2016	0.87679
2017	0.84364