Year	Percent
1990	68.66
1991	69.15
1992	69.96
1993	70.79
1994	71.44
1995	71.82
1996	72.22
1997	72.5
1998	72.88
1999	73.02
2000	73.04
2001	72.81
2002	72.52
2003	72.15
2004	71.83
2005	71.59
2006	71.54
2007	71.68
2008	72.04
2009	72.36
2010	72.47
2011	72.21
2012	71.92
2013	71.6
2014	71.33
2015	71.2
2016	71.1
2017	71.11
2018	71.17
2019	71.21