| Year | Value | | 2014 | -5.5050289405952 | | 2013 | -5.7605130367683 | | 2012 | -11.868809790613 | | 2011 | -14.737061692598 | | 2010 | -21.702775359375 | | 2009 | -24.720789395292 | | 2008 | -26.966162357463 | | 2007 | -28.354140734132 | | 2006 | -40.718825064288 | | 2005 | -45.396040634289 | | 2004 | -52.079225469347 | | 2003 | -50.695675359923 | | 2002 | -55.089369724829 | | 2001 | -54.012370034827 | | 2000 | -58.613313790907 | | 1999 | -71.673392206386 | | 1998 | -77.498111507772 | | 1997 | -66.532064072778 | | 1996 | -83.243647660603 | | 1995 | -85.289672589256 | | 1994 | -80.693635510981 | | 1993 | -74.46819971599 | | 1992 | -81.753059558874 | | 1991 | -95.267981785409 | | 1990 | -121.52917032274 | | 1989 | -130.93681829338 | | 1988 | -135.75518072945 | | 1987 | -131.75443383572 | | 1986 | -129.18314791724 | | 1985 | -117.62227739698 | | 1984 | -113.00925439596 | | 1983 | -77.53011338079 | | 1982 | -49.310284922517 | | 1981 | -29.785814871647 | | 1980 | -48.457935214942 | | 1979 | -53.697253833306 | | 1978 | -43.487194190073 | | 1977 | -39.642442112401 | | 1976 | -28.716842845169 | | 1975 | 6.6994654575697 | | 1974 | 16.377352737466 | | 1973 | 0.37331752567537 | | 1972 | 0.73265519976757 | | 1971 | 18.462311368508 |
|