Year	Percent
1990	70.08
1991	70.39
1992	70.61
1993	70.72
1994	70.83
1995	70.98
1996	70.9
1997	70.94
1998	71.02
1999	71.06
2000	71.02
2001	71.14
2002	71.27
2003	71.41
2004	71.6
2005	71.83
2006	72.01
2007	72.18
2008	72.28
2009	72.31
2010	72.38
2011	72.22
2012	72.04
2013	71.95
2014	71.89
2015	71.83
2016	71.82
2017	71.84
2018	71.88
2019	71.91