Year	Percent
1990	68.96
1991	69.05
1992	69.15
1993	69.22
1994	69.31
1995	69.48
1996	69.55
1997	69.74
1998	69.99
1999	70.18
2000	70.32
2001	70.48
2002	70.69
2003	70.84
2004	71.06
2005	70.93
2006	70.82
2007	70.7
2008	70.59
2009	70.47
2010	70.35
2011	70.24
2012	74.6
2013	71.32
2014	71.56
2015	70.92
2016	71.41
2017	71.29
2018	71.68
2019	72.08