Year	Percent
1990	66.27
1991	66.93
1992	67.36
1993	67.71
1994	68.59
1995	69.1
1996	69.82
1997	71.41
1998	72.47
1999	73.52
2000	74.88
2001	75.61
2002	76.31
2003	76.51
2004	76.62
2005	75.07
2006	75.37
2007	76.77
2008	77.85
2009	78.1
2010	77.9
2011	78.05
2012	78.9
2013	79.28
2014	79
2015	79.66
2016	79.73
2017	79.79
2018	80.31
2019	80.94