Year	Percent
1960	7.05066
1961	6.94153
1962	6.6927
1963	6.55952
1964	6.24151
1965	5.9988
1966	5.75088
1967	5.50071
1968	5.30982
1969	5.19829
1970	5.14754
1971	5.15013
1972	5.08393
1973	4.86272
1974	4.46119
1975	3.93575
1976	3.43172
1977	3.08012
1978	2.90512
1979	3.15393
1980	3.52438
1981	3.89626
1982	4.21395
1983	4.38424
1984	4.40165
1985	4.33944
1986	4.2084
1987	4.08177
1988	4.003
1989	3.91567
1990	3.85436
1991	3.88968
1992	3.83747
1993	3.4761
1994	2.75962
1995	1.8542
1996	0.79557
1997	-0.05129
1998	-0.28801
1999	0.35483
2000	1.57217
2001	2.93999
2002	3.94257
2003	4.37545
2004	4.09892
2005	3.38242
2006	2.65751
2007	2.0676
2008	1.41466
2009	0.71411
2010	-0.01539
2011	-0.82997
2012	-1.58865
2013	-2.01331
2014	-1.95618
2015	-1.53784
2016	-0.94402
2017	-0.40974