Year	Percent
1991	82.591
1992	82.531
1993	82.507
1994	83.147
1995	83.921
1996	84.71
1997	84.294
1998	83.313
1999	83.122
2000	82.702
2001	81.286
2002	79.424
2003	77.057
2004	75.118
2005	73.17
2006	70.264
2007	67.005
2008	62.834
2009	58.419
2010	52.356
2011	52.087
2012	51.49
2013	51.601
2014	51.169
2015	50.428
2016	50.157
2017	50.843
2018	50.983
2019	51.024
2020	51.159
2021	51.39
2022	51.656