Year	Percent
1961	28.50258
1962	28.50258
1963	28.81835
1964	28.98454
1965	29.23384
1966	29.74904
1967	29.74904
1968	29.74904
1969	29.79059
1970	29.79059
1971	29.95679
1972	29.99834
1973	30.08144
1974	30.16453
1975	30.16453
1976	30.16453
1977	30.99551
1978	31.03706
1979	31.07861
1980	31.12016
1981	31.80156
1982	31.81818
1983	31.82649
1984	32.26691
1985	32.03424
1986	32.05086
1987	32.31677
1988	32.74057
1989	33.18099
1990	33.4469
1991	33.73774
1992	34.23633
1993	34.81802
1994	35.06731
1995	37.83447
1996	38.67376
1997	39.95347
1998	40.82599
1999	41.69852
2000	42.72062
2001	43.00316
2002	43.20259
2003	43.35217
2004	43.41865
2005	43.62639
2006	43.27738
2007	43.00316
2008	42.64584
2009	42.28852
2010	41.96443
2011	42.13811
2012	42.15556
2013	42.15556
2014	42.15556
2015	42.15556
2016	42.15556
2017	42.22204
2018	42.24697
2019	42.24697
2020	42.30514
2021	42.30514