Year	Percent
1991	55.28
1992	54.87
1993	52.5
1994	51.75
1995	60.95
1996	58.98
1997	59.8
1998	66.58
1999	68.17
2000	73.42
2001	75.65
2002	65.89
2003	63.4
2004	65.44
2005	70.55
2006	72.34
2007	74.47
2008	71.8
2009	61.42
2010	61.62
2011	62.25
2012	65.16
2013	69.56
2014	70.22
2015	73.04
2016	77.58
2017	75.63
2018	75.08
2019	70.97