Year	Percent
1960	5.1818
1961	5.49867
1962	5.74674
1963	6.48261
1964	6.74931
1965	6.5426
1966	6.32854
1967	6.13824
1968	6.01239
1969	5.92572
1970	5.89812
1971	5.26648
1972	4.32254
1973	4.29061
1974	4.20859
1975	4.09381
1976	3.98079
1977	3.70553
1978	2.86248
1979	2.84376
1980	2.85565
1981	2.8524
1982	2.83452
1983	2.7995
1984	2.68929
1985	2.59842
1986	2.55728
1987	2.48703
1988	2.36885
1989	1.98051
1990	1.68272
1991	1.39914
1992	1.17369
1993	1.06433
1994	1.1138
1995	1.26576
1996	1.44907
1997	1.81665
1998	1.91287
1999	1.84331
2000	1.69045
2001	1.53505
2002	1.39434
2003	2.04713
2004	2.3512
2005	2.25415
2006	2.16301
2007	2.06548
2008	1.9736
2009	1.87743
2010	1.79765
2011	1.69655
2012	1.61855
2013	0.87112
2014	0.79353
2015	0.87899
2016	0.98528
2017	1.07465