Year	Percent
1990	46.495
1991	46.497
1992	46.499
1993	46.499
1994	46.492
1995	46.48
1996	45.944
1997	45.409
1998	44.875
1999	44.342
2000	43.81
2001	43.28
2002	42.751
2003	42.224
2004	41.699
2005	41.175
2006	40.654
2007	40.134
2008	39.617
2009	39.102
2010	38.59
2011	38.455
2012	38.31
2013	38.145
2014	37.994
2015	37.84
2016	37.681
2017	37.429
2018	37.176
2019	36.924
2020	36.672
2021	36.419
2022	36.167
2023	35.915
2024	35.662
2025	35.41
2026	35.157
2027	34.905
2028	34.653
2029	34.4
2030	34.148