Year	Percent
1961	2.14543
1962	4.40562
1963	8.35362
1964	8.55168
1965	8.30037
1966	13.27071
1967	8.6162
1968	2.41538
1969	3.34336
1970	1.56224
1971	5.32484
1972	10.8396
1973	17.82972
1974	16.66752
1975	-1.64868
1976	5.98186
1977	5.63723
1978	2.46028
1979	15.72804
1980	11.50832
1981	10.82758
1982	8.09586
1983	8.55286
1984	7.92323
1985	7.19379
1986	6.7894
1987	9.32789
1988	8.23252
1989	8.43681
1990	10.6683
1991	13.75182
1992	8.96515
1993	9.86178
1994	9.98004
1995	9.0627
1996	7.57502
1997	6.47627
1998	8.01017
1999	3.0684
2000	3.64497
2001	3.21562
2002	3.71568
2003	3.8678
2004	5.72541
2005	4.23693
2006	6.42258
2007	5.75624
2008	8.66467
2009	6.06383
2010	8.98382
2011	8.53971
2012	7.93439
2013	6.1865
2014	3.33176
2015	2.07189
2016	3.4639
2017	2.9976