Year | Value | 2022 | 15.224438845188 | 2021 | 10.963172781799 | 2020 | 8.1731369874683 | 2019 | 16.128773443157 | 2018 | 18.094484842996 | 2017 | 14.65053475129 | 2016 | 15.575095705525 | 2015 | 12.444217461363 | 2014 | 14.082466983779 | 2013 | 8.3112377286758 | 2012 | 12.884144540357 | 2011 | 15.516837957481 | 2010 | 16.543891561243 | 2009 | 17.594116149871 | 2008 | 23.687301096625 | 2007 | 18.991888170226 | 2006 | 14.96567179373 | 2005 | 10.394927148652 | 2004 | 16.298993845073 | 2003 | 10.179820628154 | 2002 | 5.7882341706279 | 2001 | 14.150559955435 | 2000 | 7.7225259426304 | 1999 | 8.0935334098366 | 1998 | 6.9803130385821 | 1997 | 6.858661707995 | 1996 | 8.6501165788411 | 1995 | 4.4779754216299 | 1994 | 27.691187641221 | 1993 | 33.525580657139 | 1992 | 32.804567657135 | 1991 | 25.811342708321 | 1990 | 31.185502653383 | 1989 | 40.077187589541 | 1988 | 14.770279778443 | 1987 | 22.478484809676 | 1986 | 18.551000894507 | 1985 | 15.312796278961 | 1984 | 23.307002791281 | 1983 | 21.903892361528 | 1982 | 21.387990785295 | 1981 | 29.484049221979 | 1980 | 37.708585113023 | 1979 | 1.148416124118 | 1978 | 4.9368551630457 | 1977 | 6.6771724757566 | 1976 | 7.6053763711526 | 1975 | 5.1561938679359 | 1974 | 5.5050070998375 |
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