Year	Percent
1961	6.56898
1962	12.94852
1963	43.82043
1964	47.93436
1965	38.8401
1966	28.58136
1967	25.14489
1968	33.46867
1969	40.16053
1970	40.57579
1971	17.67167
1972	87.59486
1973	414.81031
1974	678.60846
1975	347.20121
1976	247.30851
1977	101.77362
1978	56.28464
1979	47.97769
1980	29.11766
1981	11.56885
1982	7.65635
1983	30.96367
1984	15.73753
1985	41.68191
1986	21.4549
1987	25.84842
1988	21.71788
1989	13.75603
1990	22.47094
1991	21.39098
1992	13.46438
1993	12.16442
1994	14.46398
1995	11.68072
1996	3.37136
1997	3.06163
1998	1.04254
1999	2.27944
2000	4.27184
2001	3.8609
2002	3.39207
2003	4.57886
2004	7.84948
2005	7.64289
2006	12.16221
2007	5.33802
2008	-0.05344
2009	4.65476
2010	8.96229
2011	3.11291
2012	1.13016
2013	1.97665
2014	5.92361
2015	4.9695
2016	4.72545
2017	4.6514