Year	Percent
1990	66.49
1991	66.82
1992	67.99
1993	68.49
1994	69.14
1995	69.44
1996	69.57
1997	69.45
1998	69.34
1999	69.18
2000	69.07
2001	68.94
2002	68.81
2003	68.66
2004	68.27
2005	67.92
2006	67.54
2007	67.04
2008	66.61
2009	66.28
2010	66.1
2011	65.93
2012	65.72
2013	65.53
2014	65.38
2015	65.23
2016	65.19
2017	65.26
2018	65.25
2019	65.19