Year	Percent
1991	79.882
1992	78.988
1993	80.649
1994	79.123
1995	79.795
1996	80.286
1997	80.369
1998	80.514
1999	80.622
2000	80.778
2001	81.138
2002	80.878
2003	80.372
2004	80.7
2005	80.859
2006	80.24
2007	79.518
2008	80.177
2009	80.543
2010	80.551
2011	80.511
2012	80.709
2013	80.507
2014	80.538
2015	80.35
2016	80.163
2017	80.209
2018	80.168
2019	80.151
2020	80.124
2021	80.061
2022	79.966