Year	Percent
1990	84.946
1991	83.913
1992	82.734
1993	82.389
1994	82.097
1995	81.551
1996	81.321
1997	81.492
1998	81.43
1999	81.9
2000	81.953
2001	81.93
2002	82.695
2003	83.079
2004	82.873
2005	82.503
2006	82.11
2007	82.419
2008	82.659
2009	81.75
2010	81.47
2011	81.511
2012	81.353
2013	81.425
2014	81.298
2015	81.761
2016	81.776
2017	81.789
2018	81.798
2019	81.799
2020	81.791
2021	81.762
2022	81.713
2023	81.66
2024	81.622
2025	81.613
2026	81.62
2027	81.652
2028	81.697
2029	81.74
2030	81.767