Year	Percent
1976	2.16
1977	2.18
1978	1.86
1979	1.96
1980	1.65
1981	1.8
1982	2.68
1983	2.22
1984	2.1
1985	2.02
1986	2.44
1987	2.71
1988	2.18
1989	1.9
1990	1.61
1991	3.93
1992	4.9
1993	5.3
1994	5.09
1995	4.25
1996	3.83
1997	3.09
1998	2.76
1999	2.75
2000	2.65
2001	3.31
2002	3.17
2003	3.42
2004	3.22
2005	3.41
2006	4.41
2007	3.55
2008	2.82
2009	4.44
2010	4.82
2011	4.76
2012	4.58
2013	4.36
2014	4.12
2015	4.58
2016	4.62
2017	5.13
2018	4.24
2019	4
2020	7.4