Year	Percent
1990	66.66
1991	66.751
1992	66.41
1993	66.179
1994	65.872
1995	65.571
1996	65.292
1997	65.037
1998	64.765
1999	64.308
2000	63.764
2001	63.307
2002	62.845
2003	62.371
2004	61.966
2005	61.631
2006	61.374
2007	61.187
2008	61.059
2009	60.955
2010	60.88
2011	60.85
2012	60.823
2013	60.807
2014	60.802
2015	60.805
2016	60.82
2017	60.773
2018	60.726
2019	60.682
2020	60.641
2021	60.605
2022	60.571
2023	60.539
2024	60.508
2025	60.479
2026	60.451
2027	60.423
2028	60.396
2029	60.37
2030	60.347