| Year | Value | | 2022 | -1.2157903201253 | | 2021 | 0.9269180616394 | | 2020 | 0.57420695924401 | | 2019 | 0.42600736703224 | | 2018 | 0.24673204228178 | | 2017 | 0.09197229374425 | | 2016 | 0.15988041212773 | | 2015 | 0.29120578684044 | | 2014 | 0.20704699976059 | | 2013 | 0.1832113846064 | | 2012 | 0.16515104012168 | | 2011 | 0.26901733176462 | | 2010 | 0.49646196338738 | | 2009 | 0.67389404645194 | | 2008 | 0.76734295914232 | | 2007 | 0.75571875541991 | | 2006 | 0.63091124485167 | | 2005 | 0.5117901164219 | | 2004 | 0.417931377926 | | 2003 | 0.3741491692913 | | 2002 | 0.29987669708469 | | 2001 | 0.93847042771206 | | 2000 | 0.63735683394349 | | 1999 | 0.63335227398725 | | 1998 | 0.62933439252591 | | 1997 | 0.62543009690006 | | 1996 | 0.62151139901728 | | 1995 | 0.61770365843696 | | 1994 | 0.6138805069296 | | 1993 | 0.61016579273025 | | 1992 | 0.60643472620176 | | 1991 | 0.60280967948003 | | 1990 | 1.7990855933319 | | 1989 | 2.6878619887403 | | 1988 | 1.8867105288789 | | 1987 | 1.9970399561275 | | 1986 | 1.9332208108373 | | 1985 | 2.0559946088714 | | 1984 | 2.1039366180201 | | 1983 | 2.1208853335775 | | 1982 | 2.1132717825334 | | 1981 | 2.0029743064089 | | 1980 | 2.0479638613619 | | 1979 | 1.9894570195716 | | 1978 | 2.0757418953253 | | 1977 | 2.2132521788555 | | 1976 | 2.2082352549753 | | 1975 | 2.3011538096943 | | 1974 | 2.2972141756691 | | 1973 | 2.3625522238483 | | 1972 | 2.4949731067031 | | 1971 | 2.4229720170788 | | 1970 | 2.5508511782932 | | 1969 | 2.8960833877323 | | 1968 | 2.8425107104895 | | 1967 | 2.6301903454949 | | 1966 | 2.634563879541 | | 1965 | 2.7540212380423 | | 1964 | 2.8806864262433 | | 1963 | 2.9537487619963 | | 1962 | 3.0567305027909 | | 1961 | 3.1208553705905 |
|