Year	Percent
1961	36.23727
1962	36.24368
1963	36.24128
1964	36.24769
1965	36.24529
1966	36.2517
1967	36.25732
1968	36.26374
1969	36.27737
1970	36.25973
1971	36.24128
1972	36.22363
1973	36.20518
1974	36.18754
1975	36.16989
1976	35.99102
1977	35.97337
1978	35.95492
1979	35.92925
1980	35.90679
1981	35.87712
1982	35.85867
1983	35.83701
1984	35.81455
1985	35.7969
1986	35.73033
1987	35.71268
1988	35.69503
1989	35.67659
1990	35.65894
1991	35.6806
1992	35.70306
1993	35.70225
1994	35.70225
1995	35.68621
1996	35.65172
1997	35.65413
1998	35.70466
1999	35.74797
2000	35.71268
2001	35.62605
2002	35.6445
2003	35.69343
2004	35.54183
2005	35.43996
2006	35.40306
2007	35.48969
2008	35.44959
2009	35.79851
2010	35.97497
2011	36.34876
2012	36.33833
2013	36.48672
2014	36.63592
2015	36.72816
2016	36.75624
2017	36.71453
2018	36.73057
2019	36.79875
2020	36.81078
2021	36.81479