Year	Percent
1991	88.699
1992	88.487
1993	88.476
1994	88.093
1995	88.231
1996	88.491
1997	88.418
1998	88.36
1999	88.646
2000	88.338
2001	88.197
2002	88.276
2003	87.961
2004	88.12
2005	87.997
2006	88.047
2007	87.749
2008	87.377
2009	87.198
2010	87.001
2011	84.42
2012	84.139
2013	83.835
2014	83.56
2015	83.488
2016	83.494
2017	83.601
2018	83.55
2019	83.496
2020	83.44
2021	83.381
2022	83.33