Year	Percent
1990	70.16
1991	72.09
1992	71.47
1993	70.78
1994	71.15
1995	70.81
1996	70.68
1997	71.03
1998	71.17
1999	71.59
2000	71.56
2001	71.77
2002	72.06
2003	72.64
2004	72.67
2005	74.04
2006	74.95
2007	75.68
2008	75.94
2009	76.37
2010	76.73
2011	77.44
2012	77.36
2013	77.7
2014	77.71
2015	77.57
2016	77.81
2017	78.06
2018	78.49
2019	79.08