Year	Percent
1961	24.69205
1962	24.80403
1963	24.91601
1964	25.028
1965	25.13998
1966	25.25196
1967	25.45726
1968	25.56924
1969	25.58791
1970	25.70922
1971	25.8212
1972	26.12915
1973	26.53042
1974	26.82904
1975	26.95035
1976	27.34229
1977	27.9302
1978	28.04218
1979	28.14483
1980	28.46211
1981	28.62075
1982	28.96603
1983	29.10601
1984	35.32102
1985	35.32102
1986	35.32102
1987	35.32102
1988	39.98694
1989	39.98694
1990	39.98694
1991	39.98694
1992	39.98694
1993	41.82531
1994	42.10526
1995	42.10526
1996	42.10526
1997	42.68785
1998	43.27044
1999	43.85302
2000	44.43561
2001	45.0182
2002	45.60078
2003	46.18328
2004	44.07428
2005	42.57186
2006	40.2711
2007	41.50803
2008	41.37738
2009	40.77641
2010	40.28742
2011	40.07839
2012	39.77604
2013	39.40836
2014	39.986
2015	41.65733
2016	41.93542
2017	42.21351
2018	42.4916
2019	42.76969
2020	43.03845
2021	43.03845