Year	Percent
1990	84.195
1991	84.32
1992	84.377
1993	84.431
1994	84.285
1995	84.038
1996	83.846
1997	83.567
1998	83.229
1999	82.872
2000	82.513
2001	82.275
2002	82.043
2003	81.82
2004	81.615
2005	81.447
2006	81.438
2007	81.405
2008	81.373
2009	81.366
2010	81.359
2011	81.435
2012	81.486
2013	81.496
2014	81.452
2015	81.347
2016	81.267
2017	81.24
2018	81.199
2019	81.148
2020	81.089
2021	81.024
2022	80.951
2023	80.876
2024	80.805
2025	80.742
2026	80.686
2027	80.638
2028	80.598
2029	80.567
2030	80.545