Year	Percent
1990	69.261
1991	69.153
1992	68.864
1993	68.812
1994	68.639
1995	68.506
1996	68.532
1997	68.645
1998	68.681
1999	68.783
2000	69.391
2001	69.804
2002	70.013
2003	69.854
2004	69.754
2005	69.636
2006	69.47
2007	69.293
2008	69.13
2009	69.357
2010	69.198
2011	68.883
2012	68.813
2013	68.79
2014	68.809
2015	68.775
2016	68.758
2017	68.742
2018	68.726
2019	68.707
2020	68.682
2021	68.651
2022	68.616
2023	68.576
2024	68.535
2025	68.493
2026	68.45
2027	68.406
2028	68.362
2029	68.319
2030	68.276