Year	Percent
1961	1.78946
1962	3.39093
1963	3.67686
1964	1.65271
1965	4.34505
1966	5.81727
1967	0.67372
1968	0.97085
1969	3.86435
1970	6.90456
1971	3.58817
1972	3.02433
1973	11.90088
1974	22.80444
1975	4.69105
1976	9.92709
1977	8.59391
1978	6.79487
1979	11.32652
1980	14.98688
1981	26.66613
1982	28.57579
1983	21.47212
1984	10.25882
1985	10.41994
1986	14.15964
1987	23.03183
1988	21.16269
1989	11.97708
1990	11.45837
1991	12.88437
1992	14.41502
1993	12.08152
1994	41.65315
1995	45.12346
1996	17.83903
1997	7.29352
1998	8.43668
1999	9.71466
2000	7.23317
2001	7.26708
2002	15.27587
2003	2.7646
2004	14.30381
2005	18.31994
2006	11.4697
2007	9.60334
2008	9.09259
2009	8.36282
2010	8.79443
2011	8.22992
2012	5.49008
2013	5.08608
2014	6.62603
2015	7.55138
2016	6.6808
2017	8.28073