Year	Percent
1990	66.74
1991	67.03
1992	67.38
1993	67.79
1994	68.1
1995	68.07
1996	68.6
1997	70.54
1998	69.79
1999	69.08
2000	69.44
2001	69.32
2002	69.36
2003	69.89
2004	70.86
2005	71.74
2006	72.54
2007	72.83
2008	72.69
2009	73.19
2010	72.82
2011	73.2
2012	74.01
2013	74.1
2014	73.54
2015	73.87
2016	74.01
2017	73.93
2018	74.35
2019	75.03