Year	Percent
1990	71.94
1991	70.319
1992	68.743
1993	67.848
1994	66.932
1995	65.306
1996	64.044
1997	65.566
1998	65.542
1999	65.811
2000	66.205
2001	66.224
2002	66.055
2003	65.826
2004	65.064
2005	64.823
2006	65.203
2007	65.364
2008	65.825
2009	64.05
2010	63.864
2011	64.042
2012	63.569
2013	62.774
2014	62.399
2015	62.288
2016	62.151
2017	61.887
2018	61.653
2019	61.432
2020	61.213
2021	60.973
2022	60.743
2023	60.528
2024	60.337
2025	60.175
2026	60.031
2027	59.92
2028	59.837
2029	59.78
2030	59.744