Year	Percent
1960	4.03514
1961	4.73709
1962	4.33799
1963	4.33738
1964	4.27831
1965	4.01965
1966	4.07796
1967	3.94727
1968	3.87457
1969	3.60424
1970	2.8988
1971	2.46725
1972	2.53915
1973	2.48272
1974	2.58022
1975	2.48033
1976	2.37269
1977	2.30024
1978	2.20516
1979	1.98892
1980	1.69511
1981	1.74368
1982	1.84486
1983	1.9498
1984	1.88428
1985	1.73913
1986	1.76125
1987	1.77188
1988	1.63424
1989	1.66549
1990	1.16502
1991	0.87268
1992	0.3853
1993	-0.74023
1994	-0.81036
1995	0.22001
1996	0.69848
1997	0.67632
1998	0.74569
1999	0.90981
2000	1.18546
2001	0.94318
2002	0.91512
2003	1.04276
2004	1.20728
2005	1.12221
2006	1.07218
2007	0.94791
2008	0.94455
2009	1.20447
2010	1.2552
2011	1.34705
2012	1.86587
2013	2.24976
2014	2.33779
2015	2.45673
2016	2.5029
2017	2.51687