Year	Percent
1991	91.453
1992	90.892
1993	91.554
1994	91.2
1995	91.131
1996	91.21
1997	90.348
1998	91.414
1999	91.057
2000	90.594
2001	90.295
2002	90.519
2003	90.402
2004	90.38
2005	90.522
2006	90.353
2007	90.384
2008	90.55
2009	90.377
2010	90.458
2011	90.356
2012	90.328
2013	89.969
2014	89.608
2015	89.731
2016	89.611
2017	89.535
2018	89.454
2019	89.401
2020	89.345
2021	89.287
2022	89.226