Year	Percent
1961	17.41358
1962	17.41358
1963	17.41358
1964	17.41358
1965	17.41358
1966	17.41358
1967	17.7692
1968	17.7692
1969	17.7692
1970	17.7692
1971	17.7692
1972	17.7692
1973	17.94701
1974	18.12482
1975	18.12482
1976	18.12482
1977	18.16038
1978	18.16038
1979	18.19595
1980	18.30263
1981	18.55156
1982	19.01387
1983	19.36949
1984	20.32966
1985	20.61415
1986	19.44061
1987	19.2628
1988	18.90718
1989	20.22297
1990	20.57859
1991	20.71302
1992	20.71302
1993	21.42425
1994	21.77987
1995	22.08019
1996	22.38051
1997	22.68083
1998	22.98115
1999	23.28147
2000	23.58179
2001	23.88211
2002	24.18243
2003	24.48275
2004	24.78307
2005	25.08339
2006	25.38371
2007	25.68403
2008	25.98435
2009	26.28467
2010	26.58499
2011	26.88528
2012	27.18556
2013	27.48585
2014	27.78613
2015	28.08642
2016	28.38656
2017	28.6867
2018	28.98684
2019	28.98684
2020	28.98684
2021	28.98684