Year	Percent
1991	89.261
1992	89.371
1993	88.304
1994	90.115
1995	88.146
1996	88.076
1997	88.695
1998	88.321
1999	88.275
2000	88.294
2001	88.258
2002	88.198
2003	88.207
2004	88.261
2005	88.178
2006	88.295
2007	88.25
2008	88.234
2009	88.236
2010	88.219
2011	88.226
2012	88.137
2013	88.006
2014	87.91
2015	87.898
2016	87.924
2017	87.928
2018	87.927
2019	87.921
2020	87.913
2021	87.907
2022	87.901