Year	Percent
1990	66.088
1991	66.033
1992	65.814
1993	65.781
1994	65.724
1995	65.616
1996	65.607
1997	65.538
1998	65.526
1999	65.486
2000	65.515
2001	65.456
2002	65.64
2003	65.717
2004	67.062
2005	66.218
2006	65.387
2007	64.553
2008	63.715
2009	62.867
2010	62.012
2011	61.161
2012	60.306
2013	59.448
2014	58.595
2015	58.497
2016	58.596
2017	58.426
2018	58.255
2019	58.083
2020	57.909
2021	57.742
2022	57.575
2023	57.414
2024	57.272
2025	57.156
2026	57.066
2027	56.998
2028	56.944
2029	56.893
2030	56.843