Year	Percent
1990	97.27
1991	97.2
1992	97.13
1993	97.05
1994	96.97
1995	96.88
1996	96.79
1997	96.68
1998	96.56
1999	96.53
2000	96.49
2001	96.43
2002	96.36
2003	96.29
2004	96.2
2005	96.12
2006	96.03
2007	95.94
2008	95.86
2009	95.77
2010	95.69
2011	95.62
2012	95.56
2013	95.5
2014	95.45
2015	95.51
2016	95.56
2017	95.61
2018	95.66
2019	95.71