Year	Percent
1961	3.3441
1962	3.3441
1963	3.3441
1964	3.34733
1965	3.34733
1966	3.34733
1967	3.3538
1968	3.36026
1969	3.36026
1970	3.36672
1971	3.36672
1972	3.37318
1973	3.37641
1974	3.37964
1975	3.38288
1976	3.38611
1977	3.38934
1978	3.3958
1979	3.3958
1980	3.3958
1981	3.3958
1982	3.3958
1983	3.40872
1984	3.42165
1985	3.42811
1986	3.4475
1987	3.45719
1988	3.46688
1989	3.47981
1990	3.4895
1991	3.4895
1992	3.49919
1993	3.46365
1994	3.46365
1995	3.46042
1996	3.46042
1997	3.45719
1998	3.46042
1999	3.46042
2000	3.78998
2001	3.79192
2002	4.11438
2003	4.43619
2004	4.75606
2005	4.73344
2006	4.72698
2007	4.73344
2008	4.70824
2009	4.69919
2010	4.663
2011	4.64233
2012	4.60032
2013	4.58643
2014	4.5874
2015	4.63328
2016	4.63974
2017	4.69118
2018	4.71693
2019	4.72181
2020	4.71383
2021	4.73738