Year	Percent
1990	83.066
1991	83.233
1992	83.107
1993	82.993
1994	82.854
1995	82.662
1996	82.334
1997	81.961
1998	81.564
1999	81.176
2000	80.819
2001	80.519
2002	80.651
2003	80.621
2004	80.47
2005	80.645
2006	80.745
2007	81.016
2008	80.998
2009	81.019
2010	81.05
2011	81.114
2012	81.29
2013	81.453
2014	81.606
2015	81.697
2016	81.878
2017	82.028
2018	82.163
2019	82.273
2020	82.362
2021	82.488
2022	82.594
2023	82.663
2024	82.691
2025	82.681
2026	82.697
2027	82.673
2028	82.608
2029	82.523
2030	82.434