Year	Percent
1960	3.01542
1961	3.12086
1962	3.05673
1963	2.95375
1964	2.88069
1965	2.75402
1966	2.63456
1967	2.63019
1968	2.84251
1969	2.89608
1970	2.55085
1971	2.42297
1972	2.49497
1973	2.36255
1974	2.29721
1975	2.30115
1976	2.20824
1977	2.21325
1978	2.07574
1979	1.98946
1980	2.04796
1981	2.00297
1982	2.11327
1983	2.12089
1984	2.10394
1985	2.05599
1986	1.93322
1987	1.99704
1988	1.88671
1989	2.68786
1990	1.79909
1991	-0.60281
1992	-0.60643
1993	-0.61017
1994	-0.61388
1995	-0.6177
1996	-0.62151
1997	-0.62543
1998	-0.62933
1999	-0.63335
2000	-0.63736
2001	-0.93847
2002	-0.29988
2003	-0.37415
2004	-0.41793
2005	-0.51179
2006	-0.63091
2007	-0.75572
2008	-0.76734
2009	-0.67389
2010	-0.49646
2011	-0.26902
2012	-0.16515
2013	-0.18321
2014	-0.20705
2015	-0.29121
2016	-0.15988
2017	-0.09197