Year	Percent
1991	92.601
1992	92.214
1993	92.393
1994	92.46
1995	92.437
1996	92.323
1997	92.475
1998	92.6
1999	92.423
2000	92.529
2001	92.557
2002	92.457
2003	92.289
2004	92.438
2005	92.4
2006	92.603
2007	92.728
2008	92.722
2009	92.648
2010	92.587
2011	92.516
2012	92.094
2013	91.738
2014	91.72
2015	91.702
2016	91.613
2017	91.595
2018	91.567
2019	91.538
2020	91.508
2021	91.479
2022	91.448