Year	Percent
1960	5.41405
1961	5.88703
1962	6.06694
1963	5.94536
1964	5.73969
1965	5.61507
1966	5.54668
1967	7.09014
1968	7.54315
1969	7.31729
1970	7.08825
1971	5.72516
1972	5.20603
1973	5.00873
1974	4.87075
1975	4.75585
1976	5.04644
1977	5.03189
1978	4.87548
1979	4.74779
1980	4.67238
1981	4.49109
1982	4.33797
1983	4.1552
1984	3.80708
1985	3.44223
1986	3.73596
1987	3.77143
1988	3.60759
1989	3.45735
1990	3.30865
1991	2.50578
1992	2.1639
1993	2.09805
1994	2.05356
1995	2.01718
1996	1.49198
1997	1.24615
1998	1.02557
1999	1.01232
2000	1.13428
2001	1.16709
2002	1.02604
2003	0.95696
2004	0.82936
2005	0.63455
2006	0.74992
2007	0.63149
2008	0.88419
2009	0.6394
2010	0.62157
2011	0.75311
2012	0.43779
2013	0.36721
2014	0.54007
2015	0.4379
2016	0.36308
2017	0.35698