Year	Percent
1991	81.671
1992	80.414
1993	79.065
1994	77.654
1995	76.236
1996	74.811
1997	73.324
1998	71.773
1999	70.898
2000	69.987
2001	69.116
2002	68.223
2003	67.317
2004	66.401
2005	65.483
2006	64.546
2007	63.618
2008	62.675
2009	61.734
2010	60.764
2011	59.771
2012	58.75
2013	57.696
2014	56.535
2015	56.742
2016	56.864
2017	56.585
2018	56.288
2019	55.981
2020	55.672
2021	55.359
2022	55.045