Year	Percent
1990	91.15
1991	90.76
1992	90.07
1993	89.11
1994	88.21
1995	86.92
1996	86.89
1997	86.64
1998	86.34
1999	86.02
2000	85.7
2001	85.51
2002	85.34
2003	85.18
2004	85.03
2005	84.89
2006	84.79
2007	84.71
2008	84.65
2009	84.58
2010	84.49
2011	84.4
2012	84.29
2013	84.15
2014	83.98
2015	83.92
2016	83.82
2017	83.77
2018	83.68
2019	83.55
2020	80.32