Year	Percent
1983	8.72
1984	10.17
1985	9.61
1986	8.38
1987	7.2
1988	6.1
1989	6.83
1990	6.24
1991	5.13
1992	5.92
1993	5.46
1994	5.08
1995	5.41
1996	5.37
1997	5
1998	4.14
1999	5.26
2000	4.19
2001	3.95
2002	3.75
2003	3.24
2004	3.26
2005	3.4
2006	2.95
2007	2.48
2008	2.18
2009	2.2
2010	1.81
2011	1.85
2012	1.37
2013	1.48
2014	1.48
2015	1.36
2016	1.19
2017	1.08