Year	Percent
1983	6.45
1984	6.67
1985	6.87
1986	6.61
1987	6.82
1988	6.32
1989	5.71
1990	4.89
1991	5.32
1992	6.32
1993	7.68
1994	8.73
1995	8.16
1996	8.82
1997	9.86
1998	9.79
1999	8.86
2000	7.92
2001	7.77
2002	8.48
2003	9.78
2004	10.73
2005	11.17
2006	10.25
2007	8.66
2008	7.52
2009	7.74
2010	6.97
2011	5.82
2012	5.38
2013	5.23
2014	4.98
2015	4.62
2016	4.12
2017	3.75
2018	3.38
2019	3.14
2020	3.81