Year	Percent
1991	82.232
1992	82.194
1993	82.275
1994	81.834
1995	81.462
1996	80.892
1997	80.28
1998	79.953
1999	79.57
2000	79.251
2001	79.204
2002	79.15
2003	79.013
2004	78.945
2005	78.936
2006	79.049
2007	78.995
2008	78.901
2009	78.757
2010	78.552
2011	78.279
2012	78.277
2013	78.241
2014	78.104
2015	77.903
2016	77.659
2017	77.657
2018	77.645
2019	77.624
2020	77.6
2021	77.566
2022	77.529