Year	Percent
1960	3.20044
1961	3.0042
1962	3.24152
1963	3.20843
1964	3.11916
1965	3.39794
1966	3.56796
1967	3.51256
1968	3.60784
1969	3.60425
1970	3.47284
1971	3.3915
1972	3.29147
1973	3.13361
1974	3.03554
1975	3.20843
1976	3.12403
1977	3.09818
1978	2.84132
1979	2.76655
1980	2.61902
1981	2.62397
1982	2.74459
1983	2.79497
1984	2.54443
1985	2.796
1986	2.80842
1987	2.97832
1988	2.89309
1989	2.91016
1990	2.88623
1991	2.74749
1992	2.9647
1993	2.68735
1994	2.73314
1995	2.30749
1996	2.16307
1997	2.01608
1998	2.15674
1999	2.03911
2000	1.70583
2001	1.70454
2002	2.08059
2003	1.97485
2004	1.84879
2005	1.5823
2006	1.4509
2007	1.46558
2008	1.37915
2009	1.60349
2010	1.51651
2011	1.4518
2012	1.40159
2013	1.41404
2014	1.47225
2015	1.50425
2016	1.61956
2017	1.64338