Year	Percent
1991	85.439
1992	85.265
1993	85.147
1994	85.186
1995	85.141
1996	85.221
1997	84.457
1998	84.289
1999	85.665
2000	85.522
2001	85.365
2002	85.213
2003	85.24
2004	85.308
2005	85.026
2006	81.963
2007	81.536
2008	81.534
2009	81.686
2010	80.756
2011	75.324
2012	74.904
2013	74.489
2014	74.11
2015	73.581
2016	73.199
2017	73.117
2018	73.013
2019	72.919
2020	72.826
2021	72.733
2022	72.641