Year	Percent
1960	2.98189
1961	2.87427
1962	2.77327
1963	2.71991
1964	2.59166
1965	2.19533
1966	2.28271
1967	2.2819
1968	2.02994
1969	1.45735
1970	0.69588
1971	-0.14372
1972	1.9089
1973	4.05089
1974	3.76061
1975	3.75572
1976	3.86043
1977	3.90081
1978	3.90009
1979	3.76027
1980	3.55696
1981	0.26613
1982	0.30973
1983	0.46134
1984	0.75892
1985	1.14582
1986	1.55564
1987	1.89948
1988	2.10952
1989	2.16324
1990	2.09054
1991	1.99503
1992	1.91363
1993	1.81881
1994	1.72636
1995	1.63058
1996	1.5245
1997	1.41653
1998	1.33369
1999	1.2842
2000	1.25677
2001	1.23582
2002	1.21545
2003	1.1984
2004	1.18845
2005	0.98862
2006	0.96823
2007	0.96248
2008	0.96002
2009	0.95552
2010	0.94562
2011	0.93477
2012	0.92443
2013	0.90927
2014	0.91102
2015	0.90909
2016	0.90415
2017	0.89901