Year	Percent
1991	76.03
1992	75.94
1993	75.84
1994	75.73
1995	75.6
1996	75.46
1997	74.62
1998	75.02
1999	74.96
2000	74.93
2001	74.49
2002	74.92
2003	74.75
2004	74.73
2005	74.63
2006	74.58
2007	74.51
2008	74.63
2009	74.66
2010	75.44
2011	75.76
2012	75.96
2013	76.71
2014	76.93
2015	76.51
2016	76.08
2017	76.17
2018	76.79
2019	75.79
2020	73.91