Year	Percent
1991	76.46447
1992	76.48068
1993	76.52466
1994	76.55818
1995	76.56634
1996	76.61917
1997	76.64755
1998	76.46147
1999	76.52917
2000	76.64808
2001	76.46137
2002	76.35172
2003	76.31627
2004	76.34861
2005	76.13262
2006	75.93819
2007	75.84351
2008	75.55267
2009	75.48055
2010	75.13956
2011	75.03517
2012	74.5477
2013	74.27251
2014	73.97018
2015	73.76498
2016	73.48113
2017	73.21737
2018	72.85903
2019	72.53242