Year	Percent
1986	2.96
1987	2.95
1988	4.24
1989	5.45
1990	6.2
1991	8.45
1992	8.58
1993	7.97
1994	6.79
1995	5.23
1996	5.06
1997	5.49
1998	6.36
1999	5.68
2000	4.66
2001	4.21
2002	4.12
2003	3.62
2004	2.98
2005	2.77
2006	2.72
2007	2.58
2008	2.95
2009	4.41
2010	4.92
2011	4.91
2012	5.34
2013	4.47
2014	4.25
2015	4.14
2016	3.95
2017	3.57
2018	3.28
2019	3.04
2020	3.54