Year	Percent
1991	92.579
1992	92.285
1993	92.742
1994	94.524
1995	93.403
1996	93.619
1997	93.695
1998	93.51
1999	92.891
2000	92.669
2001	92.626
2002	92.134
2003	86.493
2004	86.413
2005	85.174
2006	84.658
2007	83.281
2008	82.22
2009	82.327
2010	81.719
2011	81.5
2012	81.314
2013	81.177
2014	80.924
2015	80.338
2016	80.522
2017	80.503
2018	80.456
2019	80.405
2020	80.352
2021	80.299
2022	80.246