Year	Percent
1990	98.207
1991	98.097
1992	97.979
1993	97.851
1994	97.713
1995	97.559
1996	97.388
1997	97.199
1998	96.988
1999	96.944
2000	96.89
2001	96.816
2002	96.737
2003	96.66
2004	96.586
2005	96.518
2006	96.455
2007	96.396
2008	96.339
2009	96.283
2010	96.224
2011	96.157
2012	96.087
2013	96.015
2014	95.94
2015	96.034
2016	96.094
2017	96.071
2018	96.049
2019	96.026
2020	96.001
2021	95.976
2022	95.949
2023	95.921
2024	95.893
2025	95.863
2026	95.833
2027	95.803
2028	95.773
2029	95.743
2030	95.714