Year	Percent
1991	78.59
1992	78.812
1993	79.918
1994	79.485
1995	79.886
1996	78.368
1997	78.061
1998	76.414
1999	76.771
2000	75.902
2001	76.207
2002	76.537
2003	76.256
2004	75.866
2005	76.216
2006	75.785
2007	75.579
2008	76.126
2009	74.494
2010	74.04
2011	73.963
2012	75.617
2013	74.952
2014	74.699
2015	74.178
2016	73.834
2017	73.708
2018	73.614
2019	73.521
2020	73.429
2021	73.338
2022	73.248