Year	Percent
1990	87.232
1991	87.054
1992	86.897
1993	86.833
1994	86.803
1995	86.78
1996	86.885
1997	86.925
1998	87.223
1999	87.448
2000	87.611
2001	87.704
2002	87.747
2003	87.744
2004	87.423
2005	87.054
2006	86.632
2007	86.157
2008	85.628
2009	85.048
2010	84.414
2011	83.725
2012	82.977
2013	82.938
2014	82.887
2015	82.821
2016	82.757
2017	82.534
2018	82.315
2019	82.101
2020	81.892
2021	81.685
2022	81.482
2023	81.283
2024	81.086
2025	80.89
2026	80.695
2027	80.502
2028	80.309
2029	80.117
2030	79.924