Year	Percent
1991	86.499
1992	86.495
1993	86.358
1994	85.925
1995	85.793
1996	85.581
1997	85.352
1998	85.195
1999	85.043
2000	84.831
2001	84.705
2002	84.545
2003	84.164
2004	83.815
2005	83.567
2006	83.409
2007	83.338
2008	83.294
2009	83.234
2010	83.087
2011	82.912
2012	82.749
2013	83.962
2014	85.094
2015	85.049
2016	84.916
2017	84.843
2018	84.765
2019	84.681
2020	84.595
2021	84.513
2022	84.432