Year	Percent
1983	3.61
1984	4.2
1985	4.05
1986	3.64
1987	3.07
1988	2.78
1989	3.15
1990	2.86
1991	2.35
1992	2.78
1993	2.5
1994	2.38
1995	2.54
1996	2.56
1997	2.33
1998	1.99
1999	2.47
2000	2.09
2001	1.98
2002	1.84
2003	1.68
2004	1.71
2005	1.7
2006	1.54
2007	1.29
2008	1.21
2009	1.25
2010	0.98
2011	1.11
2012	0.84
2013	0.91
2014	0.91
2015	0.89
2016	0.8
2017	0.73