Year	Percent
1991	81.273
1992	81.572
1993	81.744
1994	81.745
1995	80.589
1996	80.905
1997	81.378
1998	80.883
1999	81.011
2000	81.297
2001	80.454
2002	80.562
2003	80.085
2004	79.582
2005	79.233
2006	78.703
2007	78.328
2008	79.583
2009	79.258
2010	78.445
2011	78.952
2012	78.917
2013	78.377
2014	78.246
2015	78.484
2016	78.684
2017	78.635
2018	78.559
2019	78.479
2020	78.402
2021	78.326
2022	78.249