Year	Percent
1990	73.39
1991	73.32
1992	73.29
1993	73.23
1994	73.12
1995	72.95
1996	72.78
1997	72.59
1998	72.68
1999	72.5
2000	72.3
2001	72.19
2002	72.11
2003	72.03
2004	71.92
2005	71.81
2006	71.77
2007	71.72
2008	71.69
2009	71.68
2010	71.69
2011	71.72
2012	71.84
2013	71.92
2014	72
2015	72.03
2016	72.07
2017	72.08
2018	72.09
2019	72.07
2020	69.35