Year	Percent
1987	54.4
1994	57.9
1998	54.8
1999	62.5
2000	60.7
2003	57.9
2004	58.3
2005	57.5
2006	56.9
2007	58
2008	54.6
2009	53.5
2010	53.9
2011	51
2012	51.1
2013	52.2
2014	50.6
2015	51.3
2016	50.5