Year	Percent
1983	5.03
1984	5.4
1985	5.18
1986	5.14
1987	5.05
1988	4.87
1989	4.41
1990	3.96
1991	4.06
1992	5.12
1993	4.78
1994	4.61
1995	4.53
1996	4.32
1997	4.26
1998	4.3
1999	3.86
2000	3.93
2001	4.22
2002	4.07
2003	4.06
2004	2.48
2005	1.85
2006	1.84
2007	1.83
2008	1.71
2009	1.57
2010	1.62
2011	1.58
2012	1.45
2013	1.42
2014	1.39
2015	1.37
2016	1.36
2017	1.28