Year	Percent
1983	2.56
1984	2.33
1985	2.13
1986	1.92
1987	2.06
1988	1.81
1989	1.75
1990	1.62
1991	1.76
1992	2.38
1993	2.77
1994	3.1
1995	3.4
1996	2.97
1997	3.2
1998	3.16
1999	4.27
2000	3.7
2001	4.05
2002	3.8
2003	3.11
2004	4.24
2005	3.77
2006	3.7
2007	3.36
2008	3.24
2009	4.57
2010	6.23
2011	8.41
2012	13.46
2013	16.21
2014	17.19
2015	17.51
2016	19.17
2017	18.14
2018	15.25
2019	13.37
2020	12.19