Year	Percent
1983	22.8
1986	22.3
1987	25.4
1993	30
1995	29.9
1996	24.3
2000	21
2001	20.5
2002	21.9
2003	20.8
2005	25.9
2006	25
2007	25.6
2008	24.4
2009	24.1
2010	21.7
2011	21.2
2012	19.9
2013	22.2
2014	20.7
2015	22.55
2016	24.125