Year	Percent
1990	67.514
1991	67.618
1992	67.542
1993	67.334
1994	67.099
1995	66.773
1996	66.587
1997	66.266
1998	66.122
1999	66.529
2000	66.194
2001	65.897
2002	65.532
2003	65.25
2004	64.811
2005	64.492
2006	64.213
2007	63.429
2008	62.458
2009	60.482
2010	59.403
2011	59.628
2012	60.114
2013	60.866
2014	60.987
2015	60.474
2016	62.119
2017	61.664
2018	61.219
2019	60.803
2020	60.429
2021	60.037
2022	59.694
2023	59.388
2024	59.096
2025	58.806
2026	58.469
2027	58.142
2028	57.82
2029	57.499
2030	57.175