Year	Percent
1979	6.26
1980	6.11
1981	5.78
1982	7.16
1983	9.96
1984	8.99
1985	8.26
1986	8.08
1987	8.11
1988	7.23
1989	6.18
1990	6.93
1991	9.58
1992	10.73
1993	10.87
1994	9.72
1995	8.47
1996	8.51
1997	8.36
1998	7.68
1999	6.87
2000	6.28
2001	6.74
2002	6.37
2003	5.93
2004	5.39
2005	5.03
2006	4.78
2007	4.38
2008	4.23
2009	5.56
2010	5.21
2011	5.08
2012	5.22
2013	5.66
2014	6.08
2015	6.05
2016	5.71
2017	5.59
2018	5.3
2019	5.16
2020	6.46