Year	Percent
1990	67.49
1991	67.84
1992	67.69
1993	67.82
1994	68.15
1995	68.03
1996	68.24
1997	68.36
1998	68.07
1999	68.15
2000	68.5
2001	69.92
2002	69.8
2003	70.8
2004	71.51
2005	71.04
2006	71.54
2007	71.89
2008	71.53
2009	71.8
2010	72.36
2011	71.79
2012	71.85
2013	72.15
2014	73.22
2015	72.79
2016	72.23
2017	72.8
2018	74.05
2019	74.84