Year	Percent
1961	61.33178
1962	61.91589
1963	62.46106
1964	62.5
1965	63.23988
1966	63.12305
1967	64.87539
1968	65.2648
1969	73.87072
1970	73.20872
1971	73.9486
1972	74.22118
1973	77.88162
1974	79.04984
1975	80.21807
1976	81.581
1977	83.45016
1978	82.55452
1979	81.7757
1980	81.30841
1981	80.80218
1982	80.21807
1983	80.21807
1984	80.21807
1985	80.21807
1986	81.07477
1987	81.26947
1988	81.46417
1989	81.26947
1990	81.07477
1991	80.88006
1992	81.07477
1993	80.88006
1994	80.7243
1995	79.32243
1996	77.60903
1997	76.01246
1998	74.49377
1999	73.48131
2000	72.70249
2001	72.07944
2002	71.41745
2003	71.3785
2004	71.96262
2005	70.83333
2006	70.95016
2007	71.06698
2008	71.1838
2009	71.30062
2010	71.3785
2011	71.69003
2012	72.42991
2013	73.48131
2014	74.53271
2015	75.58411
2016	76.63551
2017	77.68692
2018	78.73832
2019	79.78972
2020	80.84112
2021	81.89252