Year	Percent
1983	10.62
1984	10.32
1985	9.8
1986	7.84
1987	7.48
1988	6.82
1989	5.53
1990	4.58
1991	5.51
1992	5.97
1993	7.67
1994	8.96
1995	8.47
1996	9.64
1997	10.67
1998	9.79
1999	8.88
2000	8.55
2001	7.79
2002	9.29
2003	11.03
2004	13
2005	15.52
2006	13.76
2007	11.9
2008	10.56
2009	11.22
2010	9.83
2011	8.53
2012	8.04
2013	7.83
2014	7.75
2015	7.23
2016	7.05
2017	6.76
2018	6.2
2019	5.77
2020	7.22