Year	Percent
1960	46.15772
1961	46.19379
1962	44.70927
1963	43.71837
1964	45.52815
1965	44.61943
1966	45.14782
1967	42.08101
1968	38.86807
1969	38.49666
1970	36.32785
1971	34.35774
1972	34.23102
1973	33.62392
1974	31.5337
1975	30.53867
1976	33.19651
1977	31.85509
1978	34.54214
1979	34.99289
1980	35.43269
1981	32.66465
1982	32.5012
1983	33.15764
1984	33.31156
1985	31.54555
1986	33.67106
1987	33.27995
1988	34.38009
1989	37.85688
1990	34.65495
1991	35.04377
1992	33.9419
1993	34.11946
1994	32.29399
1995	33.09016
1996	35.7053
1997	35.78193
1998	36.57665
1999	24.53433
2000	23.54123
2001	25.04816
2002	25.38273
2003	24.45398
2004	26.52085
2005	26.68943
2006	26.6318
2007	26.97109
2008	26.82616
2009	26.97896
2010	25.84114
2011	25.797
2012	25.76898
2013	25.2754
2014	25.61845
2015	26.39209
2016	27.75364
2017	28.48902
2018	28.06477
2019	26.8758
2020	27.10918
2021	28.52895
2022	26.89645