Year	Percent
2001	48.14
2002	48.24
2003	47.79
2004	49.09
2005	49.59
2006	50.02
2007	49.85
2008	50.92
2009	52.34
2010	53
2011	54.58
2012	55.08
2013	55.98
2014	58.21
2015	61.43
2016	62.77
2017	64.53