Year	Percent
1960	2.05863
1961	2.9813
1962	3.67469
1963	4.18975
1964	4.28755
1965	4.16727
1966	3.95868
1967	3.81367
1968	3.60695
1969	3.35794
1970	3.09278
1971	2.82808
1972	2.60248
1973	2.36807
1974	2.16732
1975	2.02903
1976	1.82106
1977	1.73057
1978	1.84998
1979	2.32629
1980	3.06408
1981	4.09729
1982	4.58036
1983	4.91303
1984	5.01728
1985	4.88901
1986	4.81111
1987	4.6767
1988	4.47342
1989	4.20536
1990	3.96999
1991	3.95479
1992	3.58536
1993	3.28464
1994	3.10252
1995	2.97145
1996	2.87708
1997	2.70226
1998	2.53099
1999	2.29877
2000	1.82997
2001	1.02309
2002	0.84144
2003	0.54556
2004	0.13593
2005	-0.3584
2006	-0.90844
2007	-1.39502
2008	-1.6342
2009	-1.53553
2010	-1.17092
2011	-0.67737
2012	-0.2565
2013	0.05798
2014	0.16546
2015	0.12185
2016	0.06603
2017	0.04331