Year	Percent
1961	30.86384
1962	30.86384
1963	30.86969
1964	30.87262
1965	30.87262
1966	30.87262
1967	30.87262
1968	30.87262
1969	30.87555
1970	30.88726
1971	30.88726
1972	30.89312
1973	30.90483
1974	30.91654
1975	30.92826
1976	30.94583
1977	30.93704
1978	30.80527
1979	30.81113
1980	30.81991
1981	30.8287
1982	30.90483
1983	30.91654
1984	30.92826
1985	30.94583
1986	30.93704
1987	30.86384
1988	30.86969
1989	30.87555
1990	30.8082
1991	30.81406
1992	30.81991
1993	30.83455
1994	30.79941
1995	30.80527
1996	30.81113
1997	30.85212
1998	30.85798
1999	30.87555
2000	30.86384
2001	30.86384
2002	30.86384
2003	30.86384
2004	30.87848
2005	30.88433
2006	30.89312
2007	30.89312
2008	30.89312
2009	30.93119
2010	30.96925
2011	31.02782
2012	31.04539
2013	31.11859
2014	31.11859
2015	31.11859
2016	31.11859
2017	31.12152
2018	31.13031
2019	31.13616
2020	31.15373
2021	31.26794