Year	Percent
1961	61.76333
1962	62.03779
1963	62.39923
1964	62.72911
1965	63.29604
1966	63.39619
1967	63.72838
1968	66.85102
1969	66.50196
1970	64.22979
1971	65.0243
1972	65.06059
1973	64.81093
1974	65.13115
1975	65.02571
1976	65.18126
1977	63.97954
1978	64.57701
1979	64.20447
1980	64.51688
1981	64.50737
1982	63.88347
1983	62.9745
1984	63.33494
1985	63.36527
1986	60.98968
1987	61.31237
1988	61.4467
1989	60.80262
1990	60.45546
1991	60.24003
1992	60.65944
1993	59.89053
1994	61.06804
1995	60.31891
1996	60.55869
1997	60.16857
1998	60.38309
1999	59.05692
2000	59.2881
2001	59.31817
2002	58.1857
2003	57.20943
2004	51.40466
2005	53.39937
2006	53.27858
2007	51.85368
2008	50.67337
2009	50.01848
2010	48.9921
2011	51.56281
2012	50.38543
2013	48.39371
2014	48.7384
2015	45.31442
2016	44.53993
2017	48.34062
2018	46.6581
2019	47.12377
2020	46.25248
2021	47.25924