Year	Percent
1990	89.51
1991	89.52
1992	89.555
1993	89.596
1994	89.606
1995	89.576
1996	89.496
1997	89.384
1998	89.235
1999	89.044
2000	88.942
2001	88.856
2002	88.803
2003	88.769
2004	88.785
2005	88.82
2006	88.876
2007	89.728
2008	87.812
2009	86.723
2010	85.714
2011	86.972
2012	87.477
2013	88.29
2014	87.419
2015	87.001
2016	87.649
2017	87.568
2018	87.489
2019	87.408
2020	87.322
2021	87.231
2022	87.137
2023	87.039
2024	86.938
2025	86.835
2026	86.729
2027	86.618
2028	86.507
2029	86.399
2030	86.295