Year	Percent
1974	9.6
1975	8.21
1976	8.79
1980	9.9
1981	8.7
1982	9.6
1983	9.25
1986	6.28
1989	2.81
1990	2.83
1991	3.51
1992	3.84
1993	5.53
1994	7.6
1995	7.9
1996	8.28
1997	9.67
1998	7.74
1999	13.95
2000	15.32
2001	13.21
2002	11.39
2004	7.7
2005	7
2006	7.4
2007	8.3
2009	9.3
2010	8.2
2011	13.3
2012	12.2
2013	11.5
2014	7.6
2015	6.9
2016	5.4