Year	Percent
1990	67.57
1991	67.86
1992	68.17
1993	68.47
1994	68.74
1995	68.97
1996	69.1
1997	69.18
1998	69.24
1999	69.3
2000	69.38
2001	69.51
2002	70.11
2003	70.73
2004	71.36
2005	71.97
2006	72.79
2007	73.49
2008	74.04
2009	74.49
2010	74.89
2011	75.37
2012	75.93
2013	76.54
2014	77.17
2015	77.78
2016	78.38
2017	78.98
2018	80.08
2019	79.14