Year	Percent
1983	3.66
1984	3.43
1985	2.81
1986	2.79
1987	2.54
1988	2.44
1989	2.07
1990	2.05
1991	1.45
1992	1.44
1993	1.39
1994	1.36
1995	1.36
1996	1.01
1997	0.97
1998	1.01
1999	0.84
2000	0.8
2001	1.19
2002	1.1
2003	0.99
2004	1.13
2005	1.15
2006	1.03
2007	1.04
2008	0.91
2009	0.63
2010	0.57
2011	0.59
2012	0.54
2013	0.48
2014	0.44
2015	0.4
2016	0.38
2017	0.36