1900 -6.6 1901 -10.3 1902 -9.400001 1903 -8.900001 1904 -6.2000003 1905 -9.400001 1906 -7.7000003 1907 -10.400001 1908 -11.6 1909 -8.1 1910 -7. 1911 -5.4 1912 -8.7 1913 -7. 1914 -10. 1915 -7.3 1916 -5.3 1917 -13.400001 1918 -13.8 1919 -10.7 1920 -8.900001 1921 -8.900001 1922 -8.5 1923 -3.4 1924 -6. 1925 -9.400001 1926 -7.6 1927 -10.3 1928 -4.1 1929 -14.1 1930 -4.1 1931 -5.4 1932 -8.900001 1933 -9.7 1934 -5.6 1935 -7.1 1936 -5.1 1937 -4.3 1938 -12.900001 1939 -4.7000003 1940 -14.6 1941 -9.6 1942 -13.3 1943 -4.3 1944 -6.7000003 1945 -10.2 1946 -12.6 1947 -12.2 1948 -9.3 1949 -4.2000003 1950 -7.2000003 1951 -2.7 1952 -5. 1953 -5.2000003 1954 -12.900001 1955 -4.3 1956 -14.7 1957 -7. 1958 -4.5 1959 -3.8 1960 -11.3 1961 -8.5 1962 -10.8 1963 -12.3 1964 -10.400001 1965 -4.5 1966 -13.6 1967 -6.4 1968 -7.7000003 1969 -8.1 1970 -6.5 1971 -8.6 1972 -7.2000003 1973 -4.2000003 1974 -0.4 1975 -4.5 1976 -6.2000003 1977 -3.7 1978 -8. 1979 -12.7 1980 -5.1 1981 -3.1000001 1982 -6.6 1983 -4.2000003 1984 -3.3 1985 -13.900001 1986 -9.1 1987 -12.1 1988 -2. 1989 -2.6000001 1990 -2.1000001 1991 -11.5 1992 -4.4 1993 -6.9 1994 -5.1 1995 -5.3 1996 -8.400001 1997 -11.2 1998 -6.1 1999 -3.1000001 2000 -4.7000003 2001 -3.7 2002 -4.3 2003 -7.5 2004 -3.6000001 2005 -5.9 2006 -4.7000003 2007 -3.6000001