Year	Percent
1990	66.888
1991	66.687
1992	66.567
1993	66.554
1994	66.7
1995	66.695
1996	66.093
1997	65.309
1998	64.473
1999	63.627
2000	64.373
2001	63.016
2002	62.625
2003	62.33
2004	62.27
2005	62.927
2006	62.757
2007	62.661
2008	62.654
2009	62.768
2010	62.954
2011	63.67
2012	63.897
2013	64.207
2014	63.052
2015	63.307
2016	63.19
2017	62.99
2018	62.748
2019	62.455
2020	62.11
2021	61.589
2022	61.02
2023	60.436
2024	59.893
2025	59.425
2026	58.92
2027	58.5
2028	58.151
2029	57.847
2030	57.576