Year	Percent
1961	3.47085
1962	1.94015
1963	6.74565
1964	9.93482
1965	17.0066
1966	8.15251
1967	-3.87836
1968	12.61652
1969	11.03682
1970	2.88915
1971	5.18201
1972	15.47256
1973	20.88249
1974	24.56873
1975	29.46352
1976	28.04865
1977	67.25078
1978	73.30669
1979	37.94948
1980	51.12614
1981	75.63357
1982	27.89058
1983	123.06121
1984	35.31242
1985	20.64841
1986	41.7058
1987	39.2015
1988	33.40285
1989	28.29431
1990	31.16659
1991	20.04136
1992	11.15008
1993	31.75721
1994	30.12893
1995	43.04533
1996	39.83774
1997	19.45817
1998	17.04847
1999	13.97117
2000	27.23011
2001	34.81794
2002	22.81858
2003	28.70441
2004	14.35015
2005	14.96372
2006	80.75458
2007	18.62789
2008	19.41027
2009	15.66657
2010	16.59564
2011	13.91482
2012	15.20528
2013	15.58108
2014	16.68128
2015	16.36888
2016	17.80909
2017	13.3947