Year	Percent
1990	91.471
1991	91.451
1992	91.472
1993	91.859
1994	90.936
1995	90.213
1996	89.821
1997	89.559
1998	89.46
1999	88.61
2000	88.538
2001	87.73
2002	87.309
2003	87.072
2004	87.797
2005	88.769
2006	88.187
2007	87.961
2008	88.775
2009	89.361
2010	89.689
2011	89.758
2012	90.09
2013	90.089
2014	90.53
2015	90.639
2016	90.826
2017	90.848
2018	90.852
2019	90.84
2020	90.815
2021	90.779
2022	90.731
2023	90.672
2024	90.608
2025	90.54
2026	90.472
2027	90.401
2028	90.33
2029	90.262
2030	90.198