Year	Percent
1961	10.80449
1962	8.94647
1963	8.63949
1964	4.26725
1965	5.10563
1966	6.15343
1967	3.06413
1968	5.21217
1969	7.83908
1970	3.13876
1971	3.39593
1972	6.96219
1973	6.60403
1974	4.47107
1975	-0.5391
1976	2.21777
1977	1.78566
1978	0.49073
1979	-0.83653
1980	1.39132
1981	-0.83989
1982	0.64041
1983	1.27551
1984	1.3629
1985	1.95133
1986	2.94528
1987	5.27376
1988	4.87169
1989	4.66282
1990	3.67577
1991	2.28532
1992	0.43612
1993	-1.54336
1994	1.89691
1995	2.30496
1996	2.24802
1997	3.25594
1998	3.8752
1999	4.06213
2000	4.81936
2001	3.28173
2002	1.43682
2003	1.33824
2004	1.40191
2005	1.98548
2006	2.42801
2007	1.86581
2008	-0.48267
2009	-4.42406
2010	-0.44535
2011	-1.34993
2012	-2.99076
2013	-1.3831
2014	1.68353
2015	3.51254
2016	3.1873
2017	2.85707