Year	Percent
1990	65.32
1991	65.68
1992	65.93
1993	66.18
1994	66.55
1995	66.8
1996	66.98
1997	67.36
1998	70.03
1999	69.79
2000	69.54
2001	69.28
2002	68.99
2003	68.68
2004	71.05
2005	70.45
2006	71.81
2007	70.42
2008	70.66
2009	68.8
2010	67.83
2011	66.99
2012	67.65
2013	67.08
2014	66.85
2015	69.21
2016	71.15
2017	71.97
2018	71.03
2019	70.96