Year	Percent
1990	88.485
1991	88.502
1992	88.403
1993	88.46
1994	88.55
1995	88.491
1996	88.416
1997	88.324
1998	88.228
1999	88.14
2000	88.07
2001	88.03
2002	88
2003	87.977
2004	87.955
2005	87.933
2006	87.908
2007	87.885
2008	88.24
2009	88.047
2010	86.671
2011	85.635
2012	86.816
2013	86.435
2014	85.717
2015	86.232
2016	87.249
2017	87.238
2018	87.237
2019	87.223
2020	87.181
2021	87.124
2022	87.039
2023	86.935
2024	86.825
2025	86.72
2026	86.626
2027	86.533
2028	86.438
2029	86.336
2030	86.221