Year	Percent
1961	2.83098
1962	2.82277
1963	2.81456
1964	2.78992
1965	2.76801
1966	2.75159
1967	2.7379
1968	2.72147
1969	2.69957
1970	2.61195
1971	2.54898
1972	2.49149
1973	2.47506
1974	2.46684
1975	2.45863
1976	2.45315
1977	2.46137
1978	2.46411
1979	2.61195
1980	2.56267
1981	2.56267
1982	2.5791
1983	2.58731
1984	2.61195
1985	2.62017
1986	2.65302
1987	2.65576
1988	2.67219
1989	2.71325
1990	2.67219
1991	2.76527
1992	2.74611
1993	2.77349
1994	2.82003
1995	3.08561
1996	3.0993
1997	2.84194
1998	2.86658
1999	2.84194
2000	2.85289
2001	2.86658
2002	2.86384
2003	2.84741
2004	2.84741
2005	2.83646
2006	2.83372
2007	2.82551
2008	2.8058
2009	2.77694
2010	2.75405
2011	2.73516
2012	2.71818
2013	2.70359
2014	2.70265
2015	2.70004
2016	2.69389
2017	2.69803
2018	2.70134
2019	2.69589
2020	2.70657
2021	2.70404