Year	Percent
1983	14.76
1984	16.45
1985	17.92
1986	18.03
1987	18.07
1988	17.44
1989	16.1
1990	14.09
1991	15.78
1992	15.03
1993	15.59
1994	14.57
1995	11.98
1996	11.72
1997	10.2
1998	7.7
1999	5.8
2000	4.32
2001	3.68
2002	4.22
2003	4.48
2004	4.49
2005	4.34
2006	4.41
2007	4.98
2008	6.77
2009	12.61
2010	14.53
2011	15.35
2012	15.45
2013	13.73
2014	11.86
2015	9.91
2016	8.37
2017	6.71
2018	5.74
2019	4.95
2020	5.62