Year	Percent
1960	5.06812
1961	5.06419
1962	5.07945
1963	5.08202
1964	4.95703
1965	4.81106
1966	5.01354
1967	5.22562
1968	5.15797
1969	4.73168
1970	4.18023
1971	3.24063
1972	2.61592
1973	3.34123
1974	5.8452
1975	8.5898
1976	11.00018
1977	12.78389
1978	12.50625
1979	10.39868
1980	7.55037
1981	4.75103
1982	2.62916
1983	1.30551
1984	1.06476
1985	1.58822
1986	2.34186
1987	2.91274
1988	3.26313
1989	3.01791
1990	2.51988
1991	1.95881
1992	1.60261
1993	1.56945
1994	2.0019
1995	2.72786
1996	3.54339
1997	4.19056
1998	4.56708
1999	4.59798
2000	4.4014
2001	4.15954
2002	4.00307
2003	5.03519
2004	5.01048
2005	5.0334
2006	5.06908
2007	-4.60004
2008	7.51683
2009	7.37326
2010	7.23393
2011	7.08384
2012	4.20517
2013	4.18288
2014	4.18385
2015	4.19865
2016	4.21612
2017	4.22565