Year	Percent
1965	0.702
1966	0.64579
1967	0.71694
1968	0.69543
1969	0.66796
1970	0.64115
1971	0.58152
1972	0.6022
1973	1.06044
1974	0.96696
1975	1.52681
1976	1.37337
1977	1.6899
1978	2.69452
1979	4.06593
1980	4.29311
1981	3.11118
1982	2.28696
1983	1.81641
1984	1.55953
1985	1.75112
1986	2.09547
1987	1.82881
1988	1.51131
1989	1.49707
1990	1.30861
1991	1.07573
1992	1.40249
1993	1.26298
1994	1.42188
1995	0.79056
1996	0.88347
1997	0.99156
1998	0.81364
1999	0.81101
2000	0.67264
2001	0.73882
2002	0.42382
2003	0.40879
2004	0.63187
2005	1.04526
2006	0.77765
2007	0.75795
2008	0.83564
2009	0.9497
2010	0.7182
2011	0.65973
2012	0.00081
2013	1.19175
2014	0.82903
2015	0.63197
2016	0.65727
2017	0.77018