Year	Percent
1990	62.97
1991	64.15
1992	64.27
1993	65.18
1994	64.76
1995	64.34
1996	65.53
1997	66.14
1998	66.35
1999	67.2
2000	65.19
2001	66.3
2002	67.38
2003	68.18
2004	68.32
2005	69.32
2006	69.81
2007	69.23
2008	68.41
2009	67.83
2010	67.24
2011	66.63
2012	66.01
2013	65.39
2014	64.76
2015	64.12
2016	64.37
2017	64.58
2018	64.79
2019	65.03