Year	Percent
1991	80.254
1992	80.186
1993	80.131
1994	79.958
1995	79.84
1996	79.824
1997	79.792
1998	79.751
1999	79.663
2000	79.531
2001	79.46
2002	79.331
2003	79.183
2004	79.011
2005	78.644
2006	78.602
2007	78.588
2008	78.602
2009	78.666
2010	78.705
2011	78.734
2012	78.804
2013	78.861
2014	78.948
2015	79.006
2016	78.989
2017	79.124
2018	79.24
2019	79.324
2020	79.368
2021	79.383
2022	79.363