Year	Percent
1991	86.175
1992	86.04
1993	85.856
1994	85.315
1995	85.813
1996	85.277
1997	85.311
1998	85.17
1999	85.029
2000	84.814
2001	88.208
2002	88.212
2003	87.846
2004	87.168
2005	86.519
2006	85.667
2007	84.778
2008	84.644
2009	84.216
2010	83.376
2011	80.979
2012	80.74
2013	80.349
2014	80.007
2015	79.561
2016	79.081
2017	79.033
2018	78.94
2019	78.852
2020	78.766
2021	78.684
2022	78.605