Year	Percent
1977	6.44
1979	6.61
1983	6.59
1985	4.52
1987	5.81
1988	5.67
1989	4.53
1990	3.77
1991	4.9
1992	3.05
1993	3.56
1994	3.3
1995	3.51
1996	4.04
1997	3.91
1998	2.3
1999	2.69
2000	1.87
2001	1.51
2002	2.07
2003	2.15
2004	3.63
2005	4.85
2006	4.76
2007	4.3
2008	3.95
2009	3.69
2010	4.41
2011	4.66
2012	5.25
2013	6.78
2014	7.75
2015	8.07
2016	7.15
2017	5.54
2018	4.48
2019	3.21
2020	2.73