Year	Percent
1960	1.91919
1961	3.25852
1962	4.38618
1963	4.41819
1964	4.45495
1965	4.48206
1966	4.43742
1967	4.37987
1968	4.41447
1969	4.55919
1970	4.75098
1971	5.08668
1972	5.29228
1973	4.95143
1974	3.95824
1975	2.58461
1976	0.93644
1977	-0.47687
1978	-1.12231
1979	-0.55131
1980	1.01496
1981	2.9815
1982	4.63442
1983	5.67357
1984	5.83305
1985	5.43396
1986	4.89421
1987	4.54755
1988	4.43201
1989	4.64673
1990	5.05353
1991	5.05455
1992	5.11322
1993	4.94512
1994	4.23678
1995	3.20661
1996	2.0045
1997	1.03531
1998	0.69657
1999	1.24802
2000	2.42662
2001	3.82876
2002	4.89783
2003	5.3767
2004	5.10035
2005	4.22404
2006	3.40408
2007	2.80978
2008	2.48706
2009	2.53509
2010	2.84064
2011	3.20062
2012	3.4413
2013	3.58561
2014	3.59601
2015	3.51353
2016	3.42041
2017	3.36066