Year	Percent
1973	5.16
1975	16.7
1977	15.78
1979	8.44
1986	9.59
1988	8.2
1989	10.86
1991	12.23
1992	13.88
1993	12.45
1994	12.59
1995	9.99
1996	8.6
1997	8.29
1998	5.75
1999	6.03
2001	6.71
2003	9.99
2005	9.26
2006	7.03
2007	6.72
2008	7.18
2009	14.45
2011	13.71
2012	14.07
2013	16.11
2014	13
2015	11
2016	11.1