Year	Percent
1983	6.65
1984	5.57
1985	5.29
1986	4.7
1987	4.83
1988	4.51
1989	3.97
1990	4
1991	3.82
1992	3.65
1993	3.61
1994	2.9
1995	2.28
1996	1.82
1997	2.16
1998	2.43
1999	1.92
2000	1.82
2001	1.47
2002	1.45
2003	1.3
2004	1.5
2005	1.39
2006	1.2
2007	0.8
2008	0.52
2009	0.52
2010	0.47
2011	0.37
2012	0.38
2013	0.25
2014	0.25
2015	0.34
2016	0.86
2017	0.47