Year	Percent
1961	3.37636
1962	3.71764
1963	1.9728
1964	4.05458
1965	4.79583
1966	4.31866
1967	2.88783
1968	4.20711
1969	5.45164
1970	8.80275
1971	8.00686
1972	7.20852
1973	8.43028
1974	15.03445
1975	25.77764
1976	15.1138
1977	13.72676
1978	11.46013
1979	14.07486
1980	19.6994
1981	11.55043
1982	7.40228
1983	5.12275
1984	5.02273
1985	5.46318
1986	4.36172
1987	5.52684
1988	6.1179
1989	7.94449
1990	7.88831
1991	6.40125
1992	3.34888
1993	2.69588
1994	1.36041
1995	10.8077
1996	4.08257
1997	0.93257
1998	1.15761
1999	0.81916
2000	2.0507
2001	0.86164
2002	2.22951
2003	2.41101
2004	2.50801
2005	2.64564
2006	3.0272
2007	2.57964
2008	2.82239
2009	1.5213
2010	1.57011
2011	2.01115
2012	1.56347
2013	1.90379
2014	1.71535
2015	0.45627
2016	1.97434
2017	1.96356