Year	Percent
1991	88.064
1992	87.594
1993	87.885
1994	87.895
1995	87.898
1996	87.75
1997	87.897
1998	87.994
1999	87.707
2000	87.81
2001	87.846
2002	87.7
2003	87.371
2004	87.548
2005	87.501
2006	87.785
2007	88.026
2008	87.932
2009	87.672
2010	87.781
2011	87.683
2012	87.064
2013	86.471
2014	86.437
2015	86.401
2016	86.313
2017	86.282
2018	86.234
2019	86.184
2020	86.132
2021	86.081
2022	86.028