Year	Percent
1990	92.06
1991	92.08
1992	92.11
1993	92.21
1994	92.24
1995	92.28
1996	92.29
1997	92.32
1998	92.37
1999	92.43
2000	92.5
2001	92.53
2002	92.56
2003	92.6
2004	92.61
2005	92.66
2006	92.67
2007	92.67
2008	91.84
2009	90.89
2010	89.81
2011	89.81
2012	89.82
2013	89.83
2014	89.85
2015	89.88
2016	89.92
2017	89.98
2018	90.05
2019	90.13