Year	Percent
1961	47.44747
1962	47.61769
1963	48.5558
1964	48.45445
1965	48.45965
1966	48.70392
1967	48.46485
1968	48.85594
1969	50.20984
1970	49.60565
1971	49.78236
1972	50.44762
1973	50.39694
1974	49.80055
1975	49.325
1976	49.24834
1977	49.41206
1978	49.43284
1979	50.53337
1980	50.12668
1981	50.17086
1982	48.32322
1983	47.70864
1984	48.87154
1985	49.54329
1986	50.00195
1987	51.22851
1988	51.01542
1989	51.8392
1990	51.55334
1991	52.06008
1992	51.84829
1993	51.85998
1994	52.16663
1995	51.31427
1996	51.14665
1997	50.98814
1998	51.86778
1999	52.36542
2000	52.5954
2001	53.23077
2002	53.52702
2003	52.80979
2004	53.54521
2005	53.5621
2006	52.61359
2007	51.32986
2008	50.83222
2009	50.55806
2010	50.68929
2011	49.69531
2012	49.9032
2013	49.92399
2014	50.0942
2015	50.0903
2016	49.80055
2017	49.3276
2018	49.11711
2019	49.00537
2020	49.06514
2021	49.49001