Year	Percent
1990	88.356
1991	88.361
1992	88.348
1993	88.176
1994	87.702
1995	87.485
1996	87.401
1997	87.404
1998	87.477
1999	87.541
2000	87.525
2001	87.433
2002	87.292
2003	87.089
2004	86.954
2005	86.941
2006	87.051
2007	87.262
2008	87.524
2009	87.739
2010	87.881
2011	87.998
2012	88.054
2013	88.052
2014	88.036
2015	88.013
2016	87.972
2017	87.997
2018	88.016
2019	88.028
2020	88.031
2021	88.031
2022	88.027
2023	88.025
2024	88.038
2025	88.07
2026	88.121
2027	88.189
2028	88.268
2029	88.348
2030	88.424