Year	Percent
1960	5.51307
1961	2.77436
1962	2.65969
1963	4.41039
1964	6.80173
1965	1.21874
1966	0.24206
1967	0.91185
1968	1.32254
1969	1.18605
1970	3.23441
1971	-4.13909
1972	2.61033
1973	3.3975
1974	-0.32604
1975	-2.26502
1976	1.78156
1977	1.35417
1978	-5.20964
1979	1.87001
1980	-6.58841
1981	-5.9822
1982	-9.13892
1983	-4.98438
1984	-1.63273
1985	-1.26981
1986	-2.42817
1987	-9.79619
1988	-10.2047
1989	-10.13883
1990	-12.1281
1991	-14.47334
1992	-15.52997
1993	-14.11479
1994	-10.3583
1995	-9.03916
1996	-11.46326
1997	-7.43954
1998	-10.76583
1999	-11.52156
2000	-11.44621
2001	-12.29381
2002	-13.85124
2003	-13.81228
2004	-10.06632
2005	-10.63489
2006	-13.08246
2007	-13.32728
2008	-7.69798
2009	-12.20879
2010	-11.45623
2011	-14.90129
2012	-12.90505
2013	-10.30048
2014	-9.97601
2015	-10.77581
2016	-10.05858
2017	-7.39437