Year	Percent
1990	80.376
1991	80.156
1992	79.627
1993	79.605
1994	79.326
1995	79.128
1996	79.341
1997	79.763
1998	80.003
1999	80.36
2000	81.508
2001	82.227
2002	82.611
2003	82.508
2004	82.448
2005	82.333
2006	82.214
2007	82.05
2008	81.868
2009	82.27
2010	82.057
2011	81.482
2012	81.299
2013	81.198
2014	81.184
2015	81.059
2016	81.002
2017	80.963
2018	80.929
2019	80.89
2020	80.84
2021	80.808
2022	80.767
2023	80.725
2024	80.692
2025	80.676
2026	80.694
2027	80.726
2028	80.766
2029	80.812
2030	80.861