Year	Percent
1990	28.757
1991	28.737
1992	28.743
1993	28.751
1994	28.751
1995	28.774
1996	28.776
1997	28.782
1998	28.787
1999	28.789
2000	28.784
2001	28.785
2002	28.782
2003	28.762
2004	28.752
2005	28.735
2006	28.727
2007	28.72
2008	28.718
2009	28.721
2010	28.717
2011	28.827
2012	28.762
2013	28.812
2014	28.877
2015	28.892
2016	28.905
2017	28.908
2018	28.91
2019	28.913
2020	28.915
2021	28.918
2022	28.92
2023	28.922
2024	28.925
2025	28.927
2026	28.93
2027	28.932
2028	28.935
2029	28.937
2030	28.939