| Year | Value | | 2022 | 38.097034135395 | | 2021 | 22.463646809423 | | 2020 | 30.332120422554 | | 2019 | 30.67639715942 | | 2018 | 25.835413754828 | | 2017 | 28.459896381683 | | 2016 | 21.199024387658 | | 2015 | 15.429318066948 | | 2014 | 20.761267114984 | | 2013 | 20.386839252099 | | 2012 | 23.69934338502 | | 2011 | 19.578125588556 | | 2010 | 15.269542183335 | | 2009 | 13.859681227448 | | 2008 | 12.642857620557 | | 2007 | 13.225797653896 | | 2006 | 15.949141437411 | | 2005 | 13.583503434442 | | 2004 | 19.778728016244 | | 2003 | 17.951664350937 | | 2002 | 20.334544429502 | | 2001 | 22.396573884236 | | 1994 | 100.70850779032 | | 1993 | 20.794718263143 | | 1992 | 20.658331619421 | | 1991 | 9.127236037661 | | 1990 | 26.239029536549 | | 1989 | 19.602683592002 | | 1988 | 11.40968731863 | | 1987 | 26.716130730156 | | 1986 | 23.468407176012 | | 1985 | 19.600566226703 | | 1984 | 24.68484092922 | | 1983 | 32.638063559111 | | 1982 | 39.850812315022 | | 1981 | 17.946066483683 |
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