Year	Percent
1990	65.977
1991	65.83
1992	66.281
1993	65.98
1994	65.711
1995	65.634
1996	65.456
1997	65.404
1998	65.121
1999	65.035
2000	64.903
2001	65.278
2002	64.783
2003	64.677
2004	66.428
2005	65.661
2006	64.902
2007	64.153
2008	63.406
2009	62.65
2010	61.883
2011	61.11
2012	60.325
2013	59.527
2014	58.717
2015	59.211
2016	58.827
2017	58.702
2018	58.573
2019	58.442
2020	58.313
2021	58.197
2022	58.084
2023	57.98
2024	57.899
2025	57.849
2026	57.835
2027	57.848
2028	57.881
2029	57.924
2030	57.971