Year	Percent
1990	91.948
1991	91.541
1992	91.063
1993	90.515
1994	89.903
1995	89.231
1996	88.526
1997	87.745
1998	86.879
1999	86.268
2000	85.614
2001	85.098
2002	84.593
2003	84.107
2004	83.652
2005	83.235
2006	82.815
2007	82.422
2008	82.063
2009	81.747
2010	81.481
2011	81.25
2012	81.064
2013	80.905
2014	80.749
2015	81.055
2016	81.333
2017	81.456
2018	81.548
2019	81.594
2020	81.587
2021	81.523
2022	81.409
2023	81.262
2024	81.103
2025	80.945
2026	80.781
2027	80.62
2028	80.468
2029	80.329
2030	80.209