Year	Percent
1996	43.3
1997	66.8
1998	66.8
1999	73.8
2000	75.6
2001	78.2
2002	64.7
2003	64.6
2004	61.5
2005	64.1
2006	64.5
2007	67
2008	63.4
2009	60.9
2010	62.6
2011	60
2012	56.3
2013	51.4
2014	47.2
2015	46.7
2016	45.5