Year | Value | 2022 | 1.4837319329426 | 2021 | 1.4111195881338 | 2020 | 1.3942206988053 | 2019 | 1.4512711273205 | 2018 | 1.4969026069056 | 2017 | 1.5364256772846 | 2016 | 1.5304690366047 | 2015 | 1.7594359154565 | 2014 | 1.8969150447766 | 2013 | 1.8412403143407 | 2012 | 1.8456064391908 | 2011 | 1.6841226569035 | 2010 | 1.7079050545418 | 2009 | 1.7613607563154 | 2008 | 1.9617766026149 | 2007 | 1.4890475837354 | 2006 | 1.4662269840476 | 2005 | 1.717004422633 | 2004 | 1.8965033050301 | 2003 | 2.1454833982387 | 2002 | 1.9903337146294 | 2001 | 2.3204467435097 | 2000 | 2.0629715134384 | 1999 | 2.133287094912 | 1998 | 2.691110859569 | 1997 | 2.2736103006683 | 1996 | 1.9868075425052 | 1995 | 2.0961622579114 | 1994 | 2.2503012342463 | 1993 | 1.9163498098859 | 1992 | 2.5061188334696 | 1991 | 2.6883248571772 | 1990 | 2.8158833188461 | 1989 | 2.1562886995001 | 1988 | 2.0209813195781 | 1987 | 2.3772631764952 | 1986 | 2.3455492283238 | 1985 | 2.0139925254392 | 1984 | 2.1708417360685 | 1983 | 1.4993207031893 | 1982 | 1.9818473003102 | 1981 | 3.9022033217009 | 1980 | 3.1723998932354 | 1979 | 2.708461077834 | 1978 | 2.5989700980918 | 1977 | 2.2474994408521 | 1976 | 2.3671565745844 | 1975 | 2.3712371151253 | 1974 | 1.8366540975123 | 1973 | 1.6226362094444 | 1972 | 1.5955418941741 | 1971 | 1.3915857657529 | 1970 | 1.6122164500726 | 1969 | 1.3182248973018 | 1968 | 1.3501521846845 | 1963 | 1.3264120155932 | 1962 | 1.1586999929322 | 1961 | 1.2034639863085 |
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