Year	Percent
1990	66.314
1991	66.305
1992	66.255
1993	66.19
1994	66.107
1995	66.019
1996	66.026
1997	65.994
1998	65.943
1999	65.898
2000	65.866
2001	65.883
2002	65.933
2003	65.998
2004	66.069
2005	66.131
2006	66.181
2007	66.228
2008	66.231
2009	66.233
2010	66.251
2011	66.3
2012	62.618
2013	58.784
2014	54.84
2015	54.832
2016	54.814
2017	54.621
2018	54.428
2019	54.235
2020	54.043
2021	53.85
2022	53.657
2023	53.465
2024	53.272
2025	53.079
2026	52.887
2027	52.694
2028	52.501
2029	52.309
2030	52.116