Year | Value | 2022 | 2.6674794364347 | 2021 | 2.726008807045 | 2020 | 2.7895667311398 | 2019 | 2.7951689526276 | 2018 | 2.8123171029681 | 2017 | 2.8489819426371 | 2016 | 2.8573845508999 | 2015 | 2.8770383782028 | 2014 | 2.9593646252693 | 2013 | 3.0222479016218 | 2012 | 3.033367502143 | 2011 | 3.0007206291676 | 2010 | 2.9805644168721 | 2009 | 3.0298271232181 | 2008 | 2.9040893977782 | 2007 | 2.7639870138662 | 2006 | 2.9074193550754 | 2005 | 2.9775017724681 | 2004 | 2.9627224639694 | 2003 | 3.0807309022829 | 2002 | 3.0398927345097 | 2001 | 2.8287316316031 | 2000 | 2.8203467600526 | 1999 | 2.84795637108 | 1998 | 2.7624198702441 | 1997 | 2.6263292988247 | 1996 | 2.6719054024038 | 1995 | 3.1358471068325 | 1994 | 3.3230806861251 | 1993 | 3.1482058329466 | 1992 | 2.8274922938739 | 1991 | 2.4497743807329 | 1990 | 2.5601459347714 | 1989 | 2.6449955154817 | 1988 | 2.5839083445233 | 1987 | 2.6941125806894 | 1986 | 2.7369689675108 | 1985 | 2.8344486512519 | 1984 | 2.8309633973 | 1983 | 2.761745282334 | 1982 | 2.5154126376973 | 1981 | 2.4186536821852 | 1980 | 2.8567018829042 | 1979 | 3.1529218663791 | 1978 | 3.100771457177 | 1977 | 2.9226544203099 | 1976 | 2.886763262853 | 1975 | 2.8988472709593 | 1974 | 2.8430452937343 | 1973 | 2.7337845608265 | 1972 | 2.6690278388142 | 1971 | 2.6709829667148 | 1970 | 2.6448123150908 | 1969 | 2.6117169957311 | 1968 | 2.584616596836 | 1967 | 2.5525593451738 | 1966 | 2.5434394782688 | 1965 | 2.5360661009466 | 1964 | 2.5034685146796 | 1963 | 2.4620218353186 | 1962 | 2.4150035424155 | 1961 | 2.3376334869573 |
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