Year | Value | 2021 | 2.142 | 2019 | 2.303 | 2017 | 2.158 | 2013 | 1.876 | 2011 | 1.843 | 1999 | 1.364 | 1998 | 1.267 | 1997 | 1.281 | 1996 | 1.245 | 1995 | 1.214 | 1994 | 1.184 | 1993 | 1.155 | 1992 | 1.128 | 1990 | 1.074 | 1988 | 1.185 | 1985 | 1.467 | 1984 | 0.927 | 1981 | 0.767 | 1975 | 0.624 | 1970 | 0.492 | 1965 | 0.4 | 1960 | 0.374 |
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