| Year | Value | | 2022 | 0.88918359497278 | | 2021 | 0.91063311297316 | | 2020 | 0.98948262660797 | | 2019 | 0.91561264090943 | | 2018 | 1.0483682308377 | | 2017 | 0.98319780230419 | | 2016 | 1.2573796239035 | | 2015 | 1.2439272469509 | | 2014 | 1.0677846601606 | | 2013 | 0.9950191199229 | | 2012 | 1.1006638753309 | | 2011 | 1.0070578622866 | | 2010 | 1.1271051005622 | | 2009 | 1.2517357257755 | | 2008 | 1.1017046812579 | | 2007 | 1.1508330294867 | | 2006 | 1.0865795610188 | | 2005 | 1.0580653075157 | | 2004 | 1.0960734430421 | | 2003 | 1.0067518242091 | | 1997 | 0.57720448326358 | | 1996 | 0.61181446396684 | | 1994 | 0.73159790750804 | | 1993 | 0.97350096510473 | | 1992 | 1.0170868034317 | | 1991 | 0.99400386251556 | | 1990 | 0.96477473288964 | | 1989 | 1.3303746583052 | | 1988 | 1.2491406122115 | | 1987 | 1.2170987532159 | | 1986 | 1.0535286704474 | | 1985 | 0.9969695036366 | | 1984 | 1.0255904194822 | | 1983 | 1.1150466249664 | | 1982 | 1.1421677056103 | | 1981 | 1.091036047831 | | 1980 | 1.1642867110098 | | 1979 | 1.1237723042115 | | 1978 | 1.0980931015143 | | 1977 | 0.79476861167002 | | 1976 | 1.1188861121028 | | 1975 | 1.1784301977232 | | 1974 | 1.339648173207 | | 1973 | 1.1303426351113 | | 1972 | 1.6956337431115 | | 1971 | 1.5003409865879 | | 1970 | 1.1810074716799 | | 1969 | 1.1487964989059 | | 1968 | 1.1604900459418 | | 1967 | 1.3126586869786 | | 1966 | 1.2635658914729 | | 1965 | 1.3196994991653 | | 1964 | 1.1439299123905 | | 1963 | 0.9989888776542 | | 1962 | 1.2755344418052 |
|