Year	Percent
1986	13.5
1989	30.8
1992	17.7
1996	13.4
1997	12.6
2000	13
2001	12.5
2002	14.6
2003	17.9
2004	23.2
2005	16.8
2006	14.2
2007	13.7
2008	14.1
2009	12.7
2010	12.4
2011	10.4
2012	11.5
2013	10.5
2014	8.3
2015	7
2016	6.2