Year	Percent
1990	58.81
1991	60.08
1992	60.53
1993	60.81
1994	61.71
1995	62.17
1996	62.27
1997	62.64
1998	63.21
1999	64.56
2000	65.22
2001	63.54
2002	63.93
2003	64.05
2004	65.07
2005	66.66
2006	66.54
2007	67.21
2008	67.2
2009	66.94
2010	67.65
2011	66.62
2012	66.79
2013	67.44
2014	67.72
2015	67.68
2016	67.73
2017	68.06
2018	68.63
2019	69.06