Year	Percent
1990	4.7
1995	23.1
1997	20.1
1999	20.1
2001	18.3
2002	27
2003	19.6
2004	17
2005	14.7
2006	19.4
2007	16.5
2008	14
2009	14.4
2010	13.3
2011	12.7
2012	9.9
2013	6.7
2014	7.5
2015	6.9
2016	7