Year | Value | 2021 | 4.3097778134275 | 2020 | 4.3057672254753 | 2019 | 4.3017566375231 | 2018 | 4.2969439319804 | 2017 | 4.2929333440282 | 2016 | 4.288922756076 | 2015 | 4.1108526509986 | 2014 | 4.0186091280982 | 2013 | 3.8862597256758 | 2012 | 3.7699526750622 | 2011 | 3.7699526750622 | 2010 | 3.3688938798428 | 2009 | 3.208470361755 | 2008 | 2.7271998074918 | 2007 | 2.7271998074918 | 2006 | 2.6469880484479 | 2005 | 2.6469880484479 | 2004 | 2.6469880484479 | 2003 | 2.6469880484479 | 2002 | 2.4865645303602 | 2001 | 2.4063527713163 | 2000 | 2.4063527713163 | 1999 | 2.4063527713163 | 1998 | 2.4063527713163 | 1997 | 2.4063527713163 | 1996 | 2.4063527713163 | 1995 | 2.4063527713163 | 1994 | 2.4063527713163 | 1993 | 2.4063527713163 | 1992 | 2.4063527713163 | 1991 | 2.3662468917943 | 1990 | 2.3261410122724 | 1989 | 2.3261410122724 | 1988 | 2.3261410122724 | 1987 | 2.3261410122724 | 1986 | 2.3261410122724 | 1985 | 2.3261410122724 | 1984 | 2.3261410122724 | 1983 | 2.3261410122724 | 1982 | 2.3261410122724 | 1981 | 2.3261410122724 | 1980 | 2.3261410122724 | 1979 | 2.3261410122724 | 1978 | 2.3261410122724 | 1977 | 2.3261410122724 | 1976 | 2.3261410122724 | 1975 | 2.3261410122724 | 1974 | 2.3261410122724 | 1973 | 2.3261410122724 | 1972 | 2.3261410122724 | 1971 | 2.3261410122724 | 1970 | 2.3261410122724 | 1969 | 2.3261410122724 | 1968 | 2.2940563086548 | 1967 | 2.2699927809417 | 1966 | 2.2459292532285 | 1965 | 2.2218657255154 | 1964 | 2.2058233737066 | 1963 | 2.1817598459934 | 1962 | 2.1657174941846 | 1961 | 2.1416539664715 |
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