| Year | Value | | 2022 | 72.308835989121 | | 2021 | 19.596492691332 | | 2020 | 12.278957446257 | | 2019 | 15.176821572002 | | 2018 | 16.332463898893 | | 2017 | 11.144311084077 | | 2016 | 7.7751341532833 | | 2015 | 7.6708536484588 | | 2014 | 8.8545727136432 | | 2013 | 7.4930903054769 | | 2012 | 8.8915699651216 | | 2011 | 6.471879671151 | | 2010 | 8.5664442055298 | | 2009 | 6.2509766309063 | | 2008 | 10.444128376489 | | 2007 | 8.7561809097264 | | 2006 | 9.5972421228843 | | 2005 | 8.17916036802 | | 2004 | 8.5982616811527 | | 2003 | 21.602438449057 | | 2002 | 44.964120947985 | | 2001 | 54.400188761908 | | 2000 | 54.915370581268 | | 1999 | 64.867487635076 | | 1998 | 84.641343484632 | | 1997 | 85.669361649978 | | 1996 | 80.412151138804 | | 1995 | 89.11331722485 | | 1994 | 105.2149864692 | | 1993 | 66.093842982001 | | 1992 | 70.076103869037 | | 1991 | 65.978567991895 | | 1990 | 60.303869134645 | | 1989 | 63.272552493096 | | 1988 | 68.809643383705 | | 1987 | 38.855843475841 | | 1986 | 34.610075973875 | | 1985 | 44.961730152878 | | 1984 | 48.392323134686 | | 1983 | 31.390271019845 | | 1982 | 29.137514502268 | | 1981 | 37.614782579772 | | 1980 | 94.260859880759 | | 1979 | 63.543108250634 | | 1978 | 61.897044438343 | | 1977 | 25.98533786506 | | 1976 | 17.455689389134 | | 1975 | 21.227355238584 | | 1974 | 23.89816157667 | | 1973 | 13.938165244896 | | 1972 | 15.416455722396 | | 1971 | 19.011408683768 | | 1970 | 7.92395208302 | | 1969 | 4.924193944983 | | 1968 | 6.046239661974 | | 1967 | 13.974892948168 | | 1966 | 8.4719962153922 | | 1965 | 4.5555336839482 | | 1964 | 1.1196378154312 | | 1963 | 6.3627069283231 | | 1962 | 3.8883202514651 | | 1961 | 3.1728569970826 | | 1960 | 5.6647398843931 |
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