| Year | Value | | 2015 | 4.610960544994 | | 2014 | -226.99010277393 | | 2013 | -250.31399000433 | | 2012 | -248.25983239455 | | 2011 | -262.87503998656 | | 2010 | -256.69222484173 | | 2009 | -229.19623675313 | | 2008 | -219.64361079673 | | 2007 | -195.29483153434 | | 2006 | -199.3926474127 | | 2005 | -212.44137775944 | | 2004 | -216.725221019 | | 2003 | -210.19013921442 | | 2002 | -211.44856419856 | | 2001 | -211.3766077893 | | 2000 | -218.1158084906 | | 1999 | -205.94613351118 | | 1998 | -193.04912642601 | | 1997 | -188.47577042019 | | 1996 | -175.02744773899 | | 1995 | -184.42900929206 | | 1994 | -180.67557921431 | | 1993 | -178.81052745785 | | 1992 | -180.18488246257 | | 1991 | -161.63690050362 | | 1990 | -162.46574870718 | | 1989 | -244.78140681314 | | 1988 | -223.61711914384 | | 1987 | -229.91772608743 | | 1986 | -244.55488047053 | | 1985 | -246.82279267684 | | 1984 | -283.02716108987 | | 1983 | -269.73663991107 | | 1982 | -285.04522041512 | | 1981 | -355.05562196655 | | 1980 | -487.35795147914 | | 1979 | -539.5639484417 | | 1978 | -618.62024054558 | | 1977 | -622.01845144507 | | 1976 | -652.00625575101 | | 1975 | -614.45584371267 | | 1974 | -693.6449946392 | | 1973 | -708.63341160485 | | 1972 | -783.07110729708 | | 1971 | -723.61430865642 | | 1970 | 54.34614762246 | | 1969 | 57.043977378239 | | 1968 | 65.516286270056 | | 1967 | 66.240658022377 | | 1966 | 68.761221078066 | | 1965 | 69.591100629738 | | 1964 | 68.167416614928 | | 1963 | 69.710019248836 | | 1962 | 69.217356666274 | | 1961 | 69.75669076459 | | 1960 | 72.127727974814 |
|