Year	Percent
1961	15.46738
1962	15.46738
1963	15.46738
1964	15.46738
1965	15.46738
1966	15.46738
1967	15.60188
1968	15.60188
1969	15.66913
1970	16.34163
1971	16.34163
1972	16.47613
1973	16.81237
1974	16.81237
1975	17.14862
1976	17.35037
1977	17.61937
1978	18.22461
1979	18.56086
1980	18.76261
1981	18.96436
1982	19.09886
1983	19.23336
1984	19.4351
1985	19.63685
1986	19.8386
1987	20.1076
1988	20.3766
1989	20.5111
1990	21.38534
1991	22.19233
1992	22.19233
1993	22.52858
1994	22.86483
1995	22.86483
1996	22.99933
1997	23.06658
1998	22.93208
1999	22.66308
2000	22.66308
2001	22.63618
2002	22.60928
2003	22.44788
2004	22.42098
2005	22.39408
2006	22.36718
2007	22.34028
2008	22.64963
2009	22.75723
2010	22.73033
2011	22.77068
2012	22.8043
2013	22.83793
2014	22.87155
2015	22.90518
2016	22.9388
2017	22.97243
2018	23.00605
2019	22.95898
2020	22.95898
2021	22.95898