Year	Percent
1960	2.8364
1961	1.49881
1962	1.50683
1963	1.55129
1964	1.63603
1965	1.64248
1966	1.56811
1967	1.50361
1968	1.40395
1969	1.32609
1970	1.2785
1971	1.20742
1972	1.01305
1973	0.98829
1974	0.962
1975	0.90392
1976	0.80459
1977	0.72801
1978	0.65717
1979	0.58911
1980	0.50356
1981	0.41524
1982	0.14737
1983	0.00639
1984	-0.00756
1985	-0.00102
1986	-0.02449
1987	-0.01974
1988	0.01837
1989	0.04505
1990	0.05374
1991	0.03925
1992	0.12188
1993	0.15099
1994	0.11015
1995	0.09128
1996	0.11772
1997	0.14244
1998	0.11823
1999	0.1062
2000	0.1346
2001	0.14538
2002	0.29743
2003	0.62096
2004	0.82332
2005	0.66574
2006	0.47461
2007	0.67868
2008	0.83591
2009	0.62729
2010	0.48044
2011	0.34307
2012	0.61958
2013	1.58784
2014	1.34137
2015	0.3257
2016	0.24613
2017	0.28729