Year	Percent
1983	8.69
1984	8.73
1985	9.67
1986	9.58
1987	9.54
1988	7.66
1989	6.42
1990	5.93
1991	7.22
1992	8.58
1993	8.75
1994	8.29
1995	7.44
1996	6.96
1997	5.87
1998	5.09
1999	4.95
2000	4.48
2001	3.83
2002	4.12
2003	3.76
2004	3.61
2005	3.44
2006	3.99
2007	3.78
2008	4.16
2009	5.85
2010	6.08
2011	6.12
2012	5.95
2013	5.66
2014	4.58
2015	4.02
2016	3.63
2017	3.19
2018	2.97
2019	2.71