Year	Percent
1983	7.91
1984	7.49
1985	6.17
1986	6.07
1987	5.5
1988	5.33
1989	4.59
1990	4.3
1991	2.92
1992	2.87
1993	2.76
1994	2.62
1995	2.65
1996	1.92
1997	1.75
1998	1.83
1999	1.52
2000	1.42
2001	2.13
2002	1.92
2003	1.69
2004	1.91
2005	1.94
2006	1.74
2007	1.77
2008	1.51
2009	1.02
2010	0.89
2011	0.88
2012	0.78
2013	0.71
2014	0.66
2015	0.58
2016	0.55
2017	0.53