Year | Value | 2022 | 26.697892661587 | 2021 | 27.079746030322 | 2020 | 24.341272328119 | 2019 | 28.723974188691 | 2018 | 28.008805747663 | 2017 | 28.83245103201 | 2016 | 24.736020928209 | 2015 | 27.468079143749 | 2014 | 24.79121024451 | 2013 | 20.681867301285 | 2012 | 17.796069130325 | 2011 | 18.269273561121 | 2010 | 18.308854710001 | 2009 | 15.343283998416 | 2008 | 19.531936938827 | 2007 | 14.299800101862 | 2006 | 12.334456321873 | 2005 | 14.872014657523 | 2004 | 16.293113462462 | 2003 | 18.769832096373 | 2002 | 20.424625362748 | 2001 | 17.012029574101 | 2000 | 15.683482459267 | 1999 | 20.063491480889 | 1998 | 20.665004396966 | 1997 | 22.914214941068 | 1996 | 25.736118028437 | 1995 | 31.117435974774 | 1994 | 25.911816079085 | 1993 | 26.638867150023 | 1992 | 28.606052044468 | 1991 | 31.056881454136 | 1990 | 30.757570261598 | 1989 | 28.777611598003 | 1988 | 31.403071939018 | 1987 | 28.573110731388 | 1986 | 25.619134007232 | 1985 | 25.061449428001 | 1984 | 29.176441876831 | 1983 | 28.820214529921 | 1982 | 32.482386464523 | 1981 | 35.119260133584 | 1980 | 31.114836367079 | 1979 | 30.019423278845 | 1978 | 28.190768230102 | 1977 | 26.609225440158 | 1976 | 31.982434090709 | 1975 | 28.267545716718 | 1974 | 17.555491463542 | 1973 | 16.411837522323 | 1972 | 20.111885424661 | 1971 | 23.601569083111 |
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