Year	Percent
1983	6.6
1986	13.3
1987	14.8
1993	19.7
1995	14.6
1996	13.7
2000	13.7
2001	14.7
2002	15.3
2003	14.5
2005	14.8
2006	14
2007	13.1
2008	12.7
2009	12.9
2010	12.5
2011	12.9
2012	12.2
2013	12.6
2014	11.9
2015	13.08
2016	15.28
2017	18.14
2018	18.27
2019	16.81