Year	Percent
1983	6.72
1984	5.32
1985	6.46
1986	6.06
1987	5.37
1988	4.72
1989	3.34
1990	3.6
1991	2.63
1992	3.68
1993	4.35
1994	7.9
1995	7.25
1996	9.23
1997	7.27
1998	6.41
1999	6.75
2000	6.38
2001	6.34
2002	6.96
2003	10.93
2004	16.91
2005	13.69
2006	16.18
2007	15.19
2008	17.87
2009	17.16
2010	14.23
2011	16.79
2012	18.76
2013	15.52
2014	22.64
2015	17.35
2016	18.88
2017	15.38
2018	14.18
2019	16.99
2020	23.2