Year | Value | 2022 | 1.6669677433245 | 2021 | 2.304928207615 | 2020 | 3.3533846899632 | 2019 | 3.2789289366488 | 2018 | 2.8341377102368 | 2017 | 3.8623442559107 | 2016 | 3.5634892018065 | 2015 | 5.4129253201192 | 2014 | 2.9506139914123 | 2013 | 3.315830961494 | 2012 | 1.8995683661395 | 2011 | 2.3034402196254 | 2010 | 2.7093522797246 | 2009 | 2.8991400763981 | 2008 | 2.3677598241437 | 2007 | 2.2399280251451 | 2006 | 1.8975717220806 | 2005 | 2.2425803053245 | 2004 | 1.6755893678971 | 1981 | 10.829534441294 | 1980 | 5.5115246670512 | 1979 | 6.1487678761116 | 1978 | 8.1177594153552 | 1977 | 9.8128134257957 | 1976 | 11.163100169561 | 1975 | 11.67462211615 | 1974 | 12.494819419775 | 1973 | 12.258362026562 | 1972 | 10.641092372823 | 1971 | 10.516111033617 | 1970 | 11.168226120858 | 1969 | 11.380084745763 | 1968 | 9.2208540042523 | 1967 | 8.4270623742455 | 1966 | 8.5205583756345 | 1965 | 8.8732665639445 | 1964 | 7.9565138939011 | 1963 | 8.2508846426044 | 1962 | 6.9108166189112 | 1961 | 6.8513988686745 | 1960 | 7.0506318589957 |
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