Year	Percent
1961	51.27904
1962	51.38751
1963	51.45982
1964	52.17391
1965	52.36373
1966	52.44509
1967	52.99647
1968	53.15918
1969	54.4337
1970	54.32523
1971	54.31619
1972	54.4337
1973	54.07213
1974	54.57832
1975	53.82808
1976	56.02459
1977	56.0969
1978	56.1421
1979	56.0969
1980	55.87092
1981	55.85284
1982	55.87996
1983	55.83476
1984	55.78957
1985	55.76245
1986	55.73533
1987	55.73533
1988	55.69918
1989	55.75341
1990	55.67206
1991	55.69014
1992	55.62686
1993	55.32857
1994	55.67206
1995	55.71726
1996	55.71726
1997	56.06978
1998	51.02594
1999	51.33327
2000	50.45648
2001	49.69719
2002	48.94301
2003	48.96571
2004	49.00699
2005	48.46281
2006	47.77686
2007	47.10432
2008	46.96621
2009	46.33382
2010	46.53648
2011	46.86809
2012	47.19049
2013	46.01142
2014	45.84562
2015	46.1671
2016	46.25092
2017	46.3294
2018	46.33382
2019	46.39831
2020	46.49042
2021	46.48671