Year | Value | 2022 | 31.665272460135 | 2021 | 31.83374492785 | 2020 | 32.026978206484 | 2019 | 32.21047798376 | 2018 | 32.396498158609 | 2017 | 32.575415283284 | 2016 | 32.747395550516 | 2015 | 32.914152925303 | 2014 | 33.075343652822 | 2013 | 33.232102795744 | 2012 | 33.386451334976 | 2011 | 33.54035713483 | 2010 | 33.700259725078 | 2009 | 33.879317688981 | 2008 | 34.07293328782 | 2007 | 34.266437993943 | 2006 | 34.460106617409 | 2005 | 34.652403712001 | 2004 | 34.843342390241 | 2003 | 35.028736954187 | 2002 | 35.203072726208 | 2001 | 35.34901655434 | 2000 | 35.470300737192 | 1999 | 35.572921075712 | 1998 | 35.669193016641 | 1997 | 35.754981852058 | 1996 | 35.827505924597 | 1995 | 35.894652309594 | 1994 | 35.982221178392 | 1993 | 36.068626999842 | 1992 | 36.155905036054 | 1991 | 36.234869620111 | 1990 | 36.336276491913 | 1989 | 36.504596957381 | 1988 | 36.833705522181 | 1987 | 37.291500513209 | 1986 | 37.751847060846 | 1985 | 38.239166108171 | 1984 | 38.780222533007 | 1983 | 39.338110830683 | 1982 | 39.887201648497 | 1981 | 40.440529549011 | 1980 | 40.95536811143 | 1979 | 41.355405814606 | 1978 | 41.845582486453 | 1977 | 42.4143676903 | 1976 | 42.988687891646 | 1975 | 43.585132983518 | 1974 | 44.205863106734 | 1973 | 44.851736487811 | 1972 | 45.504036833236 | 1971 | 46.162567832297 | 1970 | 46.846781484358 | 1969 | 47.573726318233 | 1968 | 48.310833693892 | 1967 | 49.050929429672 | 1966 | 49.792130980837 | 1965 | 50.533920005377 | 1964 | 51.290538699403 | 1963 | 52.030943161852 | 1962 | 52.771013598814 | 1961 | 53.511877906104 | 1960 | 54.257524932242 |
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