Year	Percent
1990	68.2
1991	68.76
1992	69.2
1993	69.61
1994	70.06
1995	70.5
1996	70.67
1997	70.96
1998	71.34
1999	71.69
2000	72.03
2001	72.35
2002	72.48
2003	72.57
2004	72.64
2005	72.64
2006	72.67
2007	72.72
2008	72.86
2009	72.97
2010	73.02
2011	73.05
2012	73.08
2013	73.18
2014	73.36
2015	73.46
2016	73.66
2017	73.78
2018	73.85
2019	73.95