Year	Percent
1990	66.277
1991	65.882
1992	65.517
1993	65.064
1994	64.549
1995	64.021
1996	63.509
1997	63.047
1998	62.655
1999	62.237
2000	61.802
2001	61.439
2002	61.062
2003	60.728
2004	61.232
2005	61.757
2006	62.233
2007	62.74
2008	64.12
2009	62.183
2010	60.454
2011	59.839
2012	60.334
2013	60.462
2014	60.655
2015	61.902
2016	62.036
2017	62.015
2018	61.993
2019	61.966
2020	61.932
2021	61.823
2022	61.708
2023	61.586
2024	61.455
2025	61.314
2026	61.101
2027	60.879
2028	60.656
2029	60.441
2030	60.24