Year	Percent
1990	75.061
1991	75.037
1992	74.575
1993	74.443
1994	74.116
1995	73.619
1996	71.742
1997	68.855
1998	67.793
1999	66.997
2000	66.63
2001	64.839
2002	64.175
2003	63.959
2004	63.329
2005	63.376
2006	62.851
2007	62.261
2008	61.87
2009	62.274
2010	63.175
2011	62.709
2012	62.25
2013	62.504
2014	62.851
2015	63.619
2016	63.677
2017	63.247
2018	63.12
2019	63.255
2020	63.533
2021	63.034
2022	62.568
2023	62.23
2024	62.067
2025	62.061
2026	61.857
2027	61.688
2028	61.602
2029	61.604
2030	61.671