Year	Percent
1990	68.4
1991	68.47
1992	68.96
1993	69.45
1994	70.19
1995	70.87
1996	70.79
1997	70.23
1998	69.86
1999	69.78
2000	70.28
2001	70.88
2002	71.53
2003	72.19
2004	72.79
2005	73.3
2006	73.7
2007	74.04
2008	74.36
2009	74.69
2010	75.06
2011	75.5
2012	75.96
2013	76.41
2014	76.83
2015	77.18
2016	77.46
2017	77.74
2018	78.2
2019	78.06