Year	Percent
1960	75.32407
1961	73.88717
1962	75.99761
1963	72.94795
1964	74.32404
1965	67.70392
1966	66.87473
1967	70.70633
1968	69.16821
1969	66.41938
1970	64.87511
1971	65.46078
1972	62.46014
1973	60.27145
1974	63.79496
1975	50.31146
1976	47.02772
1977	51.7872
1978	52.68035
1979	48.6845
1980	43.05661
1981	45.6518
1982	44.29864
1983	41.58056
1984	35.77134
1985	36.74289
1986	34.72854
1987	35.21085
1988	35.35041
1989	34.07163
1990	29.44225
1991	31.58085
1992	33.15941
1993	34.07709
1994	31.16929
1995	30.73058
1996	32.3287
1997	30.23252
1998	35.41378
1999	35.00259
2000	36.57556
2001	40.18193
2002	41.36694
2003	41.19553
2004	37.37173
2005	39.28052
2006	39.74508
2007	37.09451
2008	38.77501
2009	34.78481
2010	35.82139
2011	33.64676
2012	33.68099
2013	32.23501
2014	33.42904
2015	32.417
2016	35.26296
2017	35.81687
2018	37.57762
2019	36.99192
2020	38.37558
2021	36.48103
2022	41.98794