Year	Percent
1970	1.05747
1971	0.46138
1972	0.07098
1973	0.88783
1974	0.84594
1975	0.71876
1976	0.48534
1977	0.77068
1978	1.04157
1979	1.57507
1980	1.49476
1981	1.811
1982	0.75632
1983	1.54091
1984	1.29002
1985	1.03206
1986	0.89154
1987	1.76278
1988	1.44788
1989	1.1353
1990	1.0187
1991	1.06117
1992	0.97711
1993	0.89074
1994	1.83708
1995	2.62048
1996	1.9553
1997	4.09424
1998	5.75327
1999	2.94778
2000	6.28481
2001	5.00203
2002	3.86069
2003	2.62544
2004	4.38056
2005	2.33208
2006	3.8285
2007	4.44626
2008	5.72478
2009	2.75
2010	2.25206
2011	2.80059
2012	3.41279
2013	2.95671
2014	3.60821
2015	5.40104
2016	4.61003
2017	4.91211