Year	Percent
1990	83.105
1991	83.309
1992	83.424
1993	83.445
1994	83.413
1995	83.489
1996	83.463
1997	83.55
1998	83.536
1999	83.39
2000	83.413
2001	83.407
2002	83.128
2003	82.833
2004	83.154
2005	83.286
2006	83.411
2007	82.765
2008	82.512
2009	82.245
2010	82.324
2011	81.978
2012	81.234
2013	81.239
2014	81.211
2015	81.137
2016	80.868
2017	80.816
2018	80.746
2019	80.661
2020	80.566
2021	80.477
2022	80.38
2023	80.279
2024	80.182
2025	80.094
2026	80.027
2027	79.969
2028	79.917
2029	79.869
2030	79.823