Year	Percent
1961	12.78822
1962	12.96559
1963	13.14296
1964	13.32033
1965	13.49769
1966	13.76375
1967	14.11848
1968	14.38453
1969	15.13835
1970	15.31571
1971	15.75913
1972	16.02519
1973	16.20255
1974	16.46861
1975	16.82334
1976	17.08939
1977	17.35545
1978	17.53281
1979	17.71018
1980	17.97623
1981	18.24228
1982	18.53494
1983	18.62363
1984	18.71231
1985	18.88968
1986	19.42178
1987	19.51046
1988	19.59915
1989	19.68783
1990	20.13125
1991	20.21994
1992	20.35296
1993	20.57467
1994	21.28414
1995	22.34835
1996	24.03335
1997	25.62966
1998	27.0486
1999	27.5807
2000	28.33452
2001	28.9553
2002	29.84214
2003	30.74672
2004	30.74672
2005	30.89748
2006	29.62043
2007	29.70912
2008	31.4828
2009	32.36963
2010	32.36963
2011	32.36963
2012	33.25647
2013	35.03015
2014	35.03015
2015	35.03015
2016	35.03015
2017	35.03015
2018	35.03015
2019	35.03015
2020	35.03015
2021	35.03015