| Year | Value | | 2022 | 0.99000650941887 | | 2021 | 1.0761830328328 | | 2020 | 1.0318016390531 | | 2019 | 0.94980398625636 | | 2018 | 1.0004510611992 | | 2017 | 1.1957304707836 | | 2016 | 1.1155585560507 | | 2015 | 1.1743559111143 | | 2014 | 1.2522950595075 | | 2013 | 1.2759722557896 | | 2012 | 1.1812101587616 | | 2011 | 1.2142618592273 | | 2010 | 1.2426381954284 | | 2009 | 1.5368550031709 | | 2008 | 1.4478710053908 | | 2007 | 1.2820086835439 | | 2006 | 1.2824784917353 | | 2005 | 1.3028524027659 | | 2004 | 1.4872721662994 | | 2003 | 1.4485950159833 | | 2002 | 1.6696507035229 | | 2001 | 1.6398505073501 | | 2000 | 1.6549484254768 | | 1999 | 1.8957131480078 | | 1998 | 1.2186501753008 | | 1997 | 1.2119665846705 | | 1996 | 1.2094781776086 | | 1995 | 1.5240615347745 | | 1994 | 2.027211264264 | | 1993 | 2.485395525128 | | 1992 | 2.3391164024862 | | 1991 | 2.9542666080936 | | 1990 | 3.6727652309538 | | 1989 | 3.8613653793876 | | 1988 | 3.8778783511362 | | 1987 | 3.5319156344471 | | 1986 | 2.7778060807028 | | 1985 | 2.5215556104939 | | 1984 | 2.8347145061843 | | 1983 | 2.9700913804137 | | 1982 | 2.8685612085588 | | 1981 | 3.0270517513459 | | 1980 | 3.055686710282 | | 1979 | 3.5902960946505 | | 1978 | 4.0476101407639 | | 1977 | 4.434050300352 | | 1976 | 4.2013617714144 | | 1975 | 4.3540579797736 | | 1974 | 3.0966076281348 | | 1973 | 3.0269419456481 | | 1972 | 2.9699381404448 | | 1971 | 2.7240493913698 | | 1970 | 3.034015882832 | | 1969 | 3.7779928643545 | | 1968 | 3.4517142284811 | | 1967 | 2.9829428814033 | | 1966 | 2.0683828881786 | | 1965 | 2.0780054946791 | | 1964 | 2.0455198418914 | | 1963 | 1.6324857890281 | | 1962 | 1.8070990196968 | | 1961 | 1.3402819668569 |
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