Year	Percent
1961	25.97792
1962	25.98202
1963	25.98612
1964	25.99021
1965	25.99431
1966	25.99759
1967	26.00251
1968	26.00251
1969	26.00251
1970	26.04349
1971	26.04349
1972	26.04349
1973	26.04349
1974	26.08446
1975	26.12544
1976	26.28853
1977	26.28689
1978	26.28689
1979	26.29099
1980	26.29099
1981	26.29345
1982	26.29345
1983	26.29345
1984	26.29345
1985	26.30984
1986	26.3123
1987	26.3123
1988	26.32623
1989	26.32623
1990	26.33033
1991	26.34262
1992	26.43277
1993	27.1761
1994	28.90533
1995	29.02745
1996	30.03631
1997	30.85585
1998	30.85585
1999	30.85585
2000	31.68769
2001	32.21547
2002	32.5228
2003	33.37677
2004	32.52854
2005	33.10304
2006	33.16369
2007	33.27105
2008	33.45463
2009	33.63853
2010	33.64312
2011	33.79802
2012	33.95291
2013	34.1078
2014	34.2627
2015	34.41759
2016	34.5733
2017	34.7282
2018	34.88309
2019	35.03799
2020	35.19288
2021	35.34777