Year	Percent
1961	12.28468
1962	12.30734
1963	12.31868
1964	12.36401
1965	12.37534
1966	12.39801
1967	12.432
1968	12.45467
1969	12.466
1970	12.51133
1971	12.52267
1972	12.568
1973	12.57933
1974	12.62466
1975	12.63599
1976	12.65866
1977	12.66999
1978	12.71532
1979	12.74932
1980	12.77199
1981	12.66546
1982	12.73912
1983	12.89665
1984	11.9005
1985	12.66772
1986	12.75839
1987	13.10063
1988	13.20263
1989	13.03037
1990	11.7883
1991	11.45059
1992	12.70059
1993	12.35267
1994	12.14869
1995	12.62466
1996	11.9107
1997	12.02403
1998	12.08069
1999	12.09202
2000	12.11469
2001	11.58205
2002	11.61605
2003	11.38939
2004	11.75204
2005	11.48005
2006	11.53672
2007	10.91682
2008	11.02108
2009	11.54539
2010	11.2897
2011	11.29308
2012	11.76954
2013	11.90133
2014	11.98468
2015	11.89795
2016	12.00676
2017	11.34264
2018	11.50935
2019	11.67309
2020	11.58862
2021	11.52105