Year	Percent
1991	80.105
1992	79.999
1993	79.875
1994	79.197
1995	79.355
1996	79.469
1997	79.094
1998	78.909
1999	78.519
2000	78.906
2001	81.117
2002	81.592
2003	82.083
2004	81.218
2005	81.012
2006	81.081
2007	80.95
2008	81.111
2009	80.803
2010	81.127
2011	81.746
2012	80.861
2013	76.531
2014	76.373
2015	75.846
2016	75.341
2017	75.325
2018	75.279
2019	75.235
2020	75.2
2021	75.17
2022	75.14