Year	Percent
1987	49.9
1994	47.6
2002	47.7
2003	48.4
2004	47
2005	48.3
2006	45.6
2007	44.7
2008	45.1
2009	45.4
2010	45.2
2011	46.5
2012	46.6
2013	46.6
2014	47.7
2015	49.2
2016	48.3