| Year | Value | | 2014 | -44.409374253308 | | 2013 | -38.956215311845 | | 2012 | -42.553470959831 | | 2011 | -44.87278383314 | | 2010 | -48.695583347794 | | 2009 | -43.156596886664 | | 2008 | -43.923565267293 | | 2007 | -46.675368346543 | | 2006 | -49.658188653847 | | 2005 | -51.393594648066 | | 2004 | -51.31343646623 | | 2003 | -48.148049010361 | | 2002 | -40.815328652899 | | 2001 | -50.110643627302 | | 2000 | -49.01637777359 | | 1999 | -44.630899254763 | | 1998 | -49.220548182432 | | 1997 | -53.658768751182 | | 1996 | -49.660031853149 | | 1995 | -47.71546695331 | | 1994 | -45.20264647754 | | 1993 | -42.708090803053 | | 1992 | -43.269195261936 | | 1991 | -41.180441684835 | | 1990 | -41.167094383828 | | 1989 | -63.637786650057 | | 1988 | -55.898400642425 | | 1987 | -52.77721464426 | | 1986 | -61.928936952213 | | 1985 | -64.96489492847 | | 1984 | -63.181655696441 | | 1983 | -53.015185301929 | | 1982 | -57.214012166487 | | 1981 | -67.968340217506 | | 1980 | -104.84077207081 | | 1979 | -122.6425466305 | | 1978 | -102.51659531077 | | 1977 | -119.21373600248 | | 1976 | -124.84736194531 | | 1975 | -111.14439995292 | | 1974 | -150.48432737065 | | 1973 | -141.81254797013 | | 1972 | -128.91370821229 | | 1971 | -110.43824237905 |
|