Year	Percent
1991	81.281
1992	80.936
1993	81.621
1994	81.31
1995	80.733
1996	80.684
1997	79.226
1998	80.935
1999	80.318
2000	79.614
2001	79.173
2002	79.704
2003	79.587
2004	79.429
2005	79.51
2006	79.226
2007	79.291
2008	79.498
2009	79.113
2010	79.213
2011	78.959
2012	79.127
2013	78.555
2014	78.02
2015	78.403
2016	78.311
2017	78.094
2018	77.952
2019	77.851
2020	77.718
2021	77.611
2022	77.499