Year	Percent
1991	79.315
1992	79.475
1993	79.157
1994	78.898
1995	78.918
1996	78.702
1997	78.566
1998	78.209
1999	77.931
2000	77.677
2001	77.562
2002	77.502
2003	77.356
2004	77.529
2005	77.54
2006	77.99
2007	77.725
2008	77.029
2009	75.235
2010	75.738
2011	76.212
2012	75.833
2013	75.717
2014	76.251
2015	76.739
2016	76.585
2017	76.481
2018	76.364
2019	76.228
2020	76.086
2021	75.963
2022	75.841