Year	Percent
1983	2.61
1985	2.36
1987	2.31
1988	2.05
1989	1.98
1990	2.13
1991	1.68
1992	1.23
1993	1.39
1994	1.28
1995	1.25
1996	1.1
1997	1.06
1998	0.88
1999	0.81
2000	0.87
2001	0.74
2002	0.58
2003	0.52
2004	0.48
2005	0.55
2006	0.54
2007	0.54
2008	0.45
2009	0.45
2010	0.63
2011	0.62
2012	0.55
2013	0.5
2014	0.5
2015	0.56
2016	0.45
2017	0.33