Year	Percent
1990	70.325
1991	70.275
1992	70.206
1993	70.147
1994	70.114
1995	70.104
1996	70.053
1997	69.996
1998	69.975
1999	69.96
2000	68.499
2001	66.939
2002	65.299
2003	63.601
2004	61.871
2005	60.129
2006	60.4
2007	60.718
2008	61.01
2009	61.284
2010	61.53
2011	61.758
2012	61.934
2013	62.085
2014	62.225
2015	62.369
2016	62.514
2017	62.44
2018	62.366
2019	62.289
2020	62.207
2021	62.12
2022	62.031
2023	61.949
2024	61.889
2025	61.858
2026	61.85
2027	61.867
2028	61.899
2029	61.934
2030	61.963