Year	Percent
1966	1.5279
1967	4.13145
1968	1.32911
1969	1.38076
1970	6.59929
1971	5.48331
1972	2.88672
1973	8.5608
1974	24.39473
1975	4.99456
1976	2.89755
1977	9.65331
1978	6.46493
1979	10.38784
1980	12.79876
1981	11.41075
1982	16.00766
1983	12.70072
1984	6.9812
1985	3.59712
1986	3.52267
1987	5.17071
1988	7.70419
1989	8.82928
1990	4.4765
1991	7.0368
1992	5.69154
1993	4.69134
1994	4.52606
1995	5.3511
1996	4.3566
1997	14.12534
1998	3.27168
1999	3.36142
2000	3.28334
2001	3.91435
2002	2.2851
2003	2.68441
2004	3.35158
2005	4.17558
2006	3.83714
2007	2.10726
2008	6.34636
2009	3.03311
2010	3.81541
2011	4.27931
2012	4.89637
2013	3.82252
2014	4.41097
2015	3.59046
2016	5.55623
2017	5.73205