Year	Percent
1960	1.24554
1961	1.13017
1962	1.04582
1963	1.04489
1964	1.15186
1965	1.3268
1966	1.50586
1967	1.64669
1968	1.76819
1969	1.85897
1970	1.91317
1971	2.00677
1972	2.07591
1973	1.975
1974	1.66078
1975	1.2311
1976	0.72775
1977	0.33076
1978	0.22104
1979	0.50185
1980	1.05341
1981	1.69044
1982	2.2052
1983	2.54285
1984	2.62987
1985	2.54869
1986	2.42904
1987	2.35809
1988	2.31764
1989	2.33122
1990	2.37516
1991	2.42762
1992	2.44255
1993	2.39571
1994	2.2681
1995	2.09555
1996	1.91088
1997	1.76737
1998	1.69677
1999	1.72507
2000	1.82106
2001	1.93439
2002	2.03136
2003	2.11724
2004	2.18182
2005	2.23304
2006	2.27903
2007	2.32913
2008	2.38381
2009	2.44198
2010	2.50113
2011	2.55557
2012	2.59639
2013	2.61224
2014	2.5975
2015	2.56184
2016	2.51933
2017	2.47961