Year	Percent
1976	11.4
1977	11.38
1978	13.43
1979	13.48
1980	10.62
1981	11.91
1982	20.18
1983	14.63
1984	13.03
1986	8.34
1988	5.6
1989	5
1990	5.65
1991	5.06
1992	3.89
1993	4.19
1994	5.43
1995	4.44
1996	6.134
1997	5.884
1998	6.258
1999	10.143
2000	9.448
2001	9.594
2002	9.32
2003	8.545
2004	8.553
2005	7.638
2006	7.421
2007	6.952
2008	7.506
2009	9.968
2010	7.4498
2011	6.3138
2012	5.6484
2013	5.5495
2014	6.3428
2015	6.0663
2016	6.3706
2017	6.6049