Year	Percent
1969	1.89
1970	1.51
1971	2.55
1972	2.7
1973	2.46
1974	1.98
1975	1.62
1976	1.61
1982	3.14
1983	3.48
1984	3.07
1985	2.83
1986	2.23
1987	2.15
1989	1.46
1990	1.83
1991	3.24
1992	5.72
1993	9.33
1994	9.58
1995	8.9
1996	9.55
1997	10.36
1998	8.94
1999	7.61
2000	5.47
2001	4.73
2002	4.97
2003	5.55
2004	6.69
2005	7.49
2006	7.07
2007	6.16
2008	6.23
2009	8.35
2010	8.61
2011	7.8
2012	7.98
2013	8.05
2014	7.95
2015	7.43
2016	6.99
2017	6.72
2018	6.36
2019	6.83
2020	8.29