Year	Percent
1990	85.159
1991	85.26
1992	85.29
1993	85.299
1994	85.138
1995	84.879
1996	84.686
1997	84.401
1998	84.054
1999	83.683
2000	83.31
2001	83.071
2002	82.835
2003	82.606
2004	82.394
2005	82.215
2006	82.208
2007	82.176
2008	82.142
2009	82.131
2010	82.123
2011	82.208
2012	82.268
2013	82.289
2014	82.254
2015	82.156
2016	82.083
2017	82.059
2018	82.019
2019	81.968
2020	81.907
2021	81.843
2022	81.771
2023	81.696
2024	81.624
2025	81.562
2026	81.513
2027	81.471
2028	81.438
2029	81.415
2030	81.402