Year	Percent
1986	16.37
1987	19.53
1989	15.51
1990	15.65
1992	17.28
1993	15.64
1994	12.7
1995	8.39
1996	10.88
1997	10.56
1998	10.63
1999	13.6
2004	9.49
2009	8.72
2010	7.15
2011	7.54
2012	8.1
2013	6.6
2014	6.94
2015	7.22
2016	7.92