Year	Percent
1990	88.407
1991	88.398
1992	88.465
1993	88.619
1994	88.922
1995	89.17
1996	87.696
1997	85.95
1998	83.931
1999	81.661
2000	82.558
2001	82.182
2002	81.615
2003	81.124
2004	79.332
2005	78.538
2006	78.512
2007	78.502
2008	78.503
2009	78.506
2010	78.823
2011	78.297
2012	77.892
2013	78.552
2014	77.306
2015	77.897
2016	77.962
2017	77.923
2018	77.906
2019	77.9
2020	77.9
2021	77.911
2022	77.931
2023	77.96
2024	77.991
2025	78.017
2026	78.037
2027	78.049
2028	78.048
2029	78.021
2030	77.962