Year	Percent
1961	27.3208
1962	27.61457
1963	27.81042
1964	29.08343
1965	30.45437
1966	32.02115
1967	32.04074
1968	33.60752
1969	35.0568
1970	36.34939
1971	36.95652
1972	36.95652
1973	40.10967
1974	40.10967
1975	41.55895
1976	43.18449
1977	44.79044
1978	46.22013
1979	47.84567
1980	49.27536
1981	50.9009
1982	52.46769
1983	52.52644
1984	53.81904
1985	52.50685
1986	51.1555
1987	49.72581
1988	48.23737
1989	46.57266
1990	43.05915
1991	43.15742
1992	42.30317
1993	41.38269
1994	41.03016
1995	40.10967
1996	39.07168
1997	38.24912
1998	37.5049
1999	36.97611
2000	36.03604
2001	35.89894
2002	35.76185
2003	35.8206
2004	35.68351
2005	35.35057
2006	35.54642
2007	35.25264
2008	35.11555
2009	35.566
2010	35.62476
2011	35.62476
2012	35.48766
2013	35.27223
2014	34.95887
2015	35.08617
2016	34.80219
2017	34.88053
2018	34.90991
2019	34.78261
2020	34.97846
2021	35.46808