Year	Percent
1979	9.9
1980	10.9
1984	12
1985	12.5
1986	12
1987	10.9
1988	10.5
1989	9.5
1990	9.7
1991	6.9
1992	7.1
1993	8.1
1994	7.4
1995	7
1996	8.8
1997	7.3
1998	6.9
1999	4.6
2000	4.1
2005	2.55
2006	2.03
2009	6.26
2010	7.29
2012	7.47
2013	8.7
2014	9.47
2015	10.95
2016	10.03