Year	Percent
1961	60.43436
1962	60.47735
1963	60.52034
1964	60.56333
1965	60.60632
1966	60.64931
1967	60.6923
1968	60.73529
1969	60.78688
1970	60.82127
1971	60.85566
1972	60.90725
1973	60.94164
1974	61.00182
1975	61.49018
1976	61.49878
1977	61.78251
1978	61.9046
1979	61.93899
1980	61.97338
1981	62.03357
1982	62.07656
1983	62.13674
1984	62.17973
1985	62.23991
1986	62.2829
1987	62.3173
1988	62.36888
1989	62.41187
1990	62.46346
1991	62.50645
1992	62.54084
1993	62.74719
1994	62.72999
1995	62.72999
1996	62.92946
1997	64.46676
1998	66.18633
1999	67.9231
2000	69.64267
2001	70.23249
2002	70.23249
2003	70.23249
2004	70.23249
2005	70.31846
2006	70.31846
2007	70.31846
2008	70.3219
2009	70.3219
2010	70.3219
2011	70.29108
2012	70.29108
2013	70.29048
2014	70.29048
2015	70.29048
2016	70.29048
2017	70.29048
2018	70.29048
2019	70.29048
2020	70.29048
2021	70.29048