Year	Percent
1987	13.3
1994	12
1998	12.5
1999	10.7
2000	11.2
2003	11.9
2004	11.8
2005	12
2006	12.1
2007	11.7
2008	12.9
2009	13.1
2010	13
2011	13.9
2012	14
2013	13.5
2014	14
2015	13.8
2016	14.1