Year	Percent
1990	68.71
1991	68.748
1992	68.789
1993	68.817
1994	68.882
1995	68.941
1996	68.981
1997	69.001
1998	68.996
1999	68.981
2000	68.189
2001	67.36
2002	66.528
2003	65.703
2004	64.889
2005	64.089
2006	63.36
2007	62.658
2008	61.98
2009	61.318
2010	60.659
2011	60.02
2012	59.388
2013	58.774
2014	58.927
2015	59.094
2016	59.282
2017	59.265
2018	59.263
2019	59.26
2020	59.249
2021	59.219
2022	59.181
2023	59.126
2024	59.043
2025	58.927
2026	58.776
2027	58.59
2028	58.383
2029	58.177
2030	57.988