Year	Percent
1990	92.037
1991	92.003
1992	91.996
1993	92.016
1994	92.058
1995	92.119
1996	92.096
1997	92.075
1998	92.054
1999	92.026
2000	91.707
2001	91.48
2002	91.228
2003	90.94
2004	90.611
2005	90.236
2006	89.806
2007	89.37
2008	88.929
2009	88.757
2010	88.569
2011	88.449
2012	88.315
2013	88.149
2014	87.937
2015	87.672
2016	87.433
2017	87.297
2018	87.194
2019	87.12
2020	87.075
2021	87.069
2022	87.091
2023	87.135
2024	87.195
2025	87.267
2026	87.358
2027	87.459
2028	87.561
2029	87.648
2030	87.709