Year	Percent
1990	67.12
1991	67.11
1992	67.37
1993	67.69
1994	68.07
1995	68.52
1996	68.67
1997	68.91
1998	69.25
1999	69.67
2000	70.1
2001	69.98
2002	69.69
2003	69.55
2004	69.56
2005	69.66
2006	69.44
2007	69.27
2008	69.18
2009	69.19
2010	69.26
2011	69.32
2012	69.31
2013	69.27
2014	69.21
2015	69.18
2016	69.16
2017	69.13
2018	70.15
2019	68.53