Year	Percent
1971	0.19
1972	0.51
1973	0.43
1974	0.47
1975	0.45
1976	0.6
1977	0.9
1978	0.75
1979	0.92
1980	0.93
1981	1.26
1982	2.66
1983	2.9
1984	2.9
1985	4.93
1986	3.5
1987	5.77
1988	3.04
1989	1.39
1990	2.21
1991	2.63
1992	1.35
1993	1.49
1994	1.35
1995	1.1
1996	1.07
1997	0.87
1998	3.4
1999	2.97
2000	2.39
2001	2.6
2002	1.82
2003	1.54
2004	1.51
2005	1.35
2006	1.22
2007	1.18
2008	1.18
2009	1.49
2010	0.62
2011	0.66
2012	0.58
2013	0.25
2014	0.58
2015	0.6
2016	0.69
2017	0.83
2018	0.77
2019	0.72
2020	1.1