Year	Percent
1990	66.49
1991	66.06
1992	66.19
1993	66.45
1994	66.8
1995	67.16
1996	66.9
1997	66.71
1998	66.7
1999	66.95
2000	67.43
2001	67.42
2002	67.65
2003	68.25
2004	69.1
2005	70.06
2006	70.43
2007	71.06
2008	71.87
2009	72.73
2010	73.52
2011	72.72
2012	72.83
2013	72.88
2014	72.97
2015	73.09
2016	73.51
2017	74.07
2018	74.63
2019	75.09