Year	Percent
1960	3.74672
1961	3.30245
1962	4.82452
1963	3.68192
1964	3.95602
1965	3.49381
1966	2.54251
1967	4.31775
1968	2.09092
1969	2.60578
1970	3.31598
1971	3.14439
1972	2.54156
1973	4.04661
1974	2.97543
1975	2.28347
1976	2.23249
1977	2.23911
1978	2.1088
1979	2.56836
1980	2.40095
1981	1.99139
1982	1.87811
1983	1.81913
1984	1.30689
1985	1.76363
1986	1.54715
1987	1.61517
1988	1.65706
1989	1.69647
1990	3.0946
1991	6.01701
1992	3.45547
1993	2.65809
1994	2.58926
1995	2.66829
1996	2.61651
1997	2.4984
1998	2.28688
1999	2.54643
2000	2.64233
2001	2.35712
2002	2.01406
2003	1.80552
2004	1.76762
2005	1.7629
2006	1.76781
2007	1.7761
2008	1.77658
2009	2.39021
2010	1.82675
2011	1.84808
2012	1.84615
2013	1.86605
2014	1.91954
2015	1.98129
2016	1.96035
2017	1.9284