Year	Percent
1990	35.218
1991	35.228
1992	35.237
1993	35.236
1994	35.224
1995	35.197
1996	35.156
1997	35.111
1998	35.076
1999	35.046
2000	34.991
2001	34.935
2002	34.871
2003	34.792
2004	34.697
2005	34.591
2006	34.486
2007	34.369
2008	34.274
2009	34.18
2010	34.292
2011	34.405
2012	34.517
2013	34.63
2014	34.1
2015	38.5
2016	36.8
2017	36.78
2018	36.76
2019	36.741
2020	36.721
2021	36.701
2022	36.681
2023	36.662
2024	36.642
2025	36.622
2026	36.602
2027	36.583
2028	36.563
2029	36.543
2030	36.523