Year	Percent
1990	92.38
1991	92.29
1992	92.18
1993	92.06
1994	91.92
1995	91.76
1996	91.57
1997	91.37
1998	91.16
1999	90.93
2000	90.69
2001	90.41
2002	90.11
2003	89.8
2004	89.5
2005	89.22
2006	88.98
2007	88.76
2008	88.55
2009	88.32
2010	88.06
2011	88.06
2012	88.03
2013	88
2014	87.97
2015	87.93
2016	87.88
2017	87.82
2018	87.75
2019	87.69