Year	Percent
1990	86.505
1991	86.414
1992	86.287
1993	86.374
1994	86.248
1995	86.261
1996	86.142
1997	85.981
1998	85.818
1999	85.597
2000	85.369
2001	85.141
2002	84.907
2003	84.669
2004	84.431
2005	84.192
2006	83.964
2007	83.732
2008	83.495
2009	83.249
2010	82.994
2011	82.74
2012	82.478
2013	82.213
2014	82.484
2015	82.701
2016	82.957
2017	82.787
2018	82.618
2019	82.449
2020	82.276
2021	82.101
2022	81.923
2023	81.741
2024	81.557
2025	81.371
2026	81.184
2027	80.993
2028	80.8
2029	80.608
2030	80.418