Year	Percent
1991	87.987
1992	87.401
1993	86.718
1994	85.958
1995	85.123
1996	84.375
1997	83.563
1998	82.675
1999	81.894
2000	81.08
2001	80.433
2002	79.835
2003	79.291
2004	78.807
2005	78.376
2006	77.977
2007	77.598
2008	77.242
2009	76.921
2010	76.634
2011	76.246
2012	75.893
2013	75.558
2014	75.1
2015	75.493
2016	75.795
2017	75.882
2018	75.936
2019	75.931
2020	75.857
2021	75.71
2022	75.506