Year	Percent
1990	70.26
1991	70.45
1992	71.24
1993	72.03
1994	72.8
1995	73.54
1996	72.33
1997	73.23
1998	73.58
1999	74.42
2000	74.91
2001	75.39
2002	76.2
2003	76.47
2004	77.17
2005	77.58
2006	77.57
2007	77.55
2008	77.65
2009	78.58
2010	77.83
2011	77.07
2012	78.2
2013	78.62
2014	78.84
2015	79.35
2016	79.24
2017	79.62
2018	79.77
2019	80.34