Year	Percent
2001	55.91
2002	56.64
2003	57.23
2004	57.54
2005	57.67
2006	57.92
2007	57.92
2008	58.02
2009	58.85
2010	58.84
2011	58.59
2012	58.75
2013	58.89
2014	58.91
2015	59.02
2016	59.17
2017	59.3