Year	Percent
1990	81.03
1991	81.14
1992	81.14
1993	81.05
1994	80.82
1995	80.66
1996	80.36
1997	80
1998	79.61
1999	79.18
2000	78.78
2001	77.91
2002	77.1
2003	76.41
2004	75.83
2005	75.43
2006	75.75
2007	76.12
2008	76.64
2009	77.07
2010	77.52
2011	78.07
2012	78.56
2013	79.05
2014	79.09
2015	79.43
2016	79.32
2017	79.35
2018	79.15
2019	78.94
2020	74.03