Year	Percent
1975	9.17
1976	5
1977	4.3
1978	1.59
1979	2.09
1980	2.4
1981	1.53
1982	1.85
1983	2.11
1984	1.92
1985	3.18
1986	2.82
1987	1.73
1988	1.36
1989	1.07
1990	1.32
1991	1.8
1992	1.96
1993	1.96
1994	1.9
1995	3.22
1996	2.83
1997	2.22
1998	4.58
1999	6.25
2000	4.92
2001	5.09
2002	7.28
2003	7.86
2004	6.74
2005	5.58
2006	4.77
2007	4.01
2008	3.56
2009	5.26
2010	4.33
2011	3.42
2012	3.29
2013	3.4
2014	3.3
2015	3.31
2016	3.39
2017	3.13
2018	2.82
2019	2.93
2020	5.83