Year	Percent
1990	66.276
1991	66.249
1992	66.074
1993	65.858
1994	66.103
1995	66.006
1996	65.931
1997	65.766
1998	65.723
1999	65.98
2000	64.426
2001	62.84
2002	62.361
2003	61.879
2004	61.395
2005	60.909
2006	60.42
2007	61.253
2008	62.08
2009	62.9
2010	59.23
2011	57.782
2012	56.32
2013	56.971
2014	57.62
2015	68.87
2016	68.738
2017	68.183
2018	67.627
2019	67.072
2020	66.517
2021	65.962
2022	65.406
2023	64.851
2024	64.296
2025	63.741
2026	63.185
2027	62.63
2028	62.075
2029	61.52
2030	60.964