| Year | Value | | 2022 | 0.79410091897918 | | 2021 | 0.87082220635925 | | 2020 | 1.0130884354632 | | 2019 | 1.0626568171493 | | 2018 | 1.1077649169891 | | 2017 | 1.1484878587273 | | 2016 | 1.169192826469 | | 2015 | 1.1864068735458 | | 2014 | 1.2136329869145 | | 2013 | 1.2310891448257 | | 2012 | 1.2381816783956 | | 2011 | 1.2060117872339 | | 2010 | 1.2246049318619 | | 2009 | 1.2383020209851 | | 2008 | 1.2485678179073 | | 2007 | 1.2427406996891 | | 2006 | 1.2576481964035 | | 2005 | 1.2637468409061 | | 2004 | 1.2749405767856 | | 2003 | 1.2891520082818 | | 2002 | 1.3136574259944 | | 2001 | 1.3349989011366 | | 2000 | 1.3531623785957 | | 1999 | 1.3807034516609 | | 1998 | 1.4190943494983 | | 1997 | 1.4535764295385 | | 1996 | 1.481536895888 | | 1995 | 1.5010592520805 | | 1994 | 1.5373133657839 | | 1993 | 1.5805510562429 | | 1992 | 1.6279990115419 | | 1991 | 1.684012890322 | | 1990 | 1.7455356528516 | | 1989 | 1.7443358127349 | | 1988 | 1.7733559089493 | | 1987 | 1.7885479681647 | | 1986 | 1.7717157967641 | | 1985 | 1.7504159445403 | | 1984 | 1.7453025546456 | | 1983 | 1.7853492116712 | | 1982 | 1.8090130535122 | | 1981 | 1.7686382531377 | | 1980 | 1.7547073816882 | | 1979 | 1.7703969476205 | | 1978 | 1.7545669962037 | | 1977 | 1.7555589646145 | | 1976 | 1.7953143380962 | | 1975 | 1.8552540554857 | | 1974 | 1.9354750263724 | | 1973 | 1.9879718345044 | | 1972 | 2.0084654698977 | | 1971 | 2.1061143361068 | | 1970 | 2.0925605445712 | | 1969 | 2.1018464544743 | | 1968 | 2.0699488841176 | | 1967 | 2.0565146842635 | | 1966 | 2.1113835560055 | | 1965 | 2.0784635506121 | | 1964 | 2.0984663577732 | | 1963 | 2.1292767565311 | | 1962 | 1.7714954041234 | | 1961 | 1.350747650788 |
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